NSTA Learning Center Professional Development Tools

Rates of Chemical Reactions

7/10/2009 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Chemical Reactions SciPack. It demonstrates how chemical reactions can take place in time periods ranging from the few femto-seconds (10-15 seconds) required for an atom to move a fraction of a chemical bond distance to geologic time scales of billions of years. The rate of reactions among atoms and molecules depends on how often they encounter one another, which is affected by the concentration, pressure (for gases), and temperature of the reacting substances. The configuration of atoms in a molecule determines the molecule's properties. Shapes are particularly important in determining how large molecules interact with others. Some atoms and molecules called catalysts are highly effective in accelerating chemical reactions. Chemical reactions in living systems are catalyzed by protein molecules called enzymes.

Matter and Energy in Reactions

7/10/2009 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the final of four Science Objects in the Chemical Reactions SciPack. It explains how different configurations of atoms and molecules are associated with different energy levels. Some changes of configuration among atoms and molecules require a net input of energy whereas others cause a net release. As a result, chemical reactions may release or consume energy. Some reactions such as the burning of fossil fuels release large amounts of energy by losing heat and by emitting light. Energy from light and other electromagnetic radiation can initiate many chemical reactions such as photosynthesis and the evolution of urban smog. The behavior of atoms in chemical reactions demonstrates the conservation of matter: When the number of atoms in a closed system stays the same, their total mass remains constant no matter how they are rearranged.

A World of Reactions

7/10/2009 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Chemical Reactions SciPack. It explains that chemical reactions occur all around us, for example in health care, cooking, cosmetics, and automobiles. An enormous variety of biological, chemical, and physical phenomena can be explained by changes in the arrangement and motion of atoms and molecules. An atom's electron configuration, particularly the outermost electrons, determines how the atom can interact with other atoms. Atoms form bonds to other atoms by transferring or sharing electrons. Carbon atoms can bond to one another in chains, rings, and branching networks to form a variety of structures, and complex chemical reactions involving these molecules take place constantly in every cell in living objects.

Categorizing Chemical Reactions

7/10/2009 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Chemical Reactions SciPack. It provides an understanding of the idea that a large number of important reactions involve the transfer of either electrons (oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting ions, molecules, or atoms. In other reactions, chemical bonds are broken by heat or light to form very reactive radicals with electrons ready to form new bonds. Reactions involving these radicals control many processes such as the presence of ozone and greenhouse gases in the atmosphere, burning and processing of fossil fuels, the formation of polymers, and explosions.

Light as Waves

5/1/2009 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Nature of Light SciPack. It provides conceptual and real world understanding of the idea that waves (including sound and seismic waves, waves on water, and light waves) have energy and can transfer energy when they interact with matter. Wave behavior can be described in terms of how fast the disturbance propagates, and of the distance between successive crests or troughs of the wave (the wavelength). Accelerating electric charges produce electromagnetic waves which can be organized into a spectrum of varying wavelengths (and frequencies): radio waves, microwaves, radiant heat or infrared radiation, visible light, ultraviolet radiation, x-rays, and gamma rays. These wavelengths vary from radio waves (the longest) to gamma rays (the shortest). Human eyes only respond to a narrow range of wavelengths of electromagnetic radiation-what we call visible light. In empty space, electromagnetic waves of all wavelengths move at the same speed-the "speed of light."

So, What is Light?

5/1/2009 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the final of four Science Objects in the Nature of Light SciPack. It provides an understanding of how sometimes the nature and behavior of electromagnetic radiation such as light can be best described using a wave model, but at other times it can be best described by using a particle model. Particles of light called photons contain discrete amounts of energy. The energy that a photon carries is directly proportional to its frequency. The energy of a photon is inversely proportional to the wavelength of the electromagnetic radiation. Each kind of atom or molecule can only gain or lose energy only in discrete amounts so they can absorb and emit light only at frequencies and wavelengths corresponding to these amounts. These combinations of wavelengths or spectra can be used to identify the substance.

Light and Color

5/1/2009 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Nature of Light SciPack. It provides conceptual and real world understanding of how the wavelengths of electromagnetic radiation affect the way they interact with different materials. We perceive differences of wavelength within the visible part of the spectrum as differences in color. Shorter wavelengths of light (blue) are scattered more by air molecules than longer wavelengths of light (red). When the atmosphere scatters sunlight-which is a mixture of all wavelengths-short-wavelength light (which gives us the sensation of blue) is scattered much more by air molecules than long-wavelength (red) light is. The atmosphere, therefore, appears blue and the sun seen through it by un-scattered light appears reddened. Also, materials that allow one range of wavelengths to pass through them may completely absorb others. For example, some gases in the atmosphere, including carbon dioxide and water vapor, are transparent to much of the incoming sunlight but absorb the infrared radiation from the warmed surface of Earth.

Characteristics of Light

5/1/2009 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Nature of Light SciPack. It establishes the concept that electromagnetic waves can interact with materials in different ways. For example, they can reflect off a material's surface. We can see an object when light waves that are emitted or reflected by the object enter the eye. Electromagnetic waves can also pass through materials, sometimes slowing down or changing direction as a result of entering and leaving the material. Or, electromagnetic waves may be absorbed or scattered within the material. Electromagnetic waves and other waves diffract around corners, and interfere with one another in predictable ways.

Resources and Human Impact: Environmental Degradation

9/30/2008 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Resources and Human Impact SciPack. It explores how human activities, such as reducing the amount of forest cover, increasing the amount and variety of chemicals that enter the atmosphere, intensive farming and fishing, and consuming fossil fuels have changed Earth's land, oceans, and atmosphere. Although the land, atmosphere, and the oceans have a limited capacity to absorb wastes and recycle materials naturally, humans have disrupted these natural cycles. Fresh water, limited in supply, is essential for life and most industrial processes. Overuse and pollution of rivers, lakes, oceans, and groundwater reduces the availability and suitability of these resources for all organisms. Technology used in the extraction and consumption of fossil fuels needed to meet the growing human demand has increased the depletion of nonrenewable energy resources such as fossil fuels, and degraded or altered the environment, both locally and globally.

Resources and Human Impact: Using Technology to Address Resource Use Issues

9/30/2008 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects in the Resources and Human Impact SciPack. It explores how human beings impact other species and the ecosystems in which they live. Due to our role in changing the environment, humans have a responsibility for preserving their habitat. There are a variety of approaches to reducing or reversing the human impact on the environment such as limiting population growth, reducing resource use, modifying population distribution, recycling resources, and the wise use of technology to solve problems. Managing resources by cleaning up polluted air, water, or soil or restoring depleted soil, forests, or fishing grounds can be difficult and costly but are critical for human health. Alternative energy resources such as wind, tides, and solar radiation can be utilized to reduce the consumption of fossil fuel-based energy sources. Social, political, and economic factors involve tradeoffs that will strongly influence the types and extent to which technologies will be developed and used.

Resources and Human Impact: Population Growth, Technology, and the Environment

9/30/2008 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Resources and Human Impact SciPack. It explores how technology can solve problems, but at the same time, can also create new strains on the environment. Improved technology used for harvesting food, coupled with the technology of improved sanitation, has accelerated the growth of the human population. A larger human population increases the impact on the environment and its resources, many of which are limited and non renewable. Due to the rapid growth of the human population and their use of technology in many parts of the world, humans have exceeded the carrying capacity of their environment, compromising human health.

Resources and Human Impact: Earth as a System

9/30/2008 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Resources and Human Impact SciPack. It explores how human beings, who live within and depend on Earth's ecosystems, modify the land, ocean, and atmosphere. In all environments, organisms, including humans, cooperate or compete with one another for resources. These resources include food, air, water, and space. The size and rate of growth of all species, including humans, are affected by these environmental factors. In turn, these environmental factors are affected by the size and rate of growth of a population. Populations are limited in growth by the carrying capacity of the environment, which is the amount of life any ecosystem can support with its available space, energy, water, and food.

Cell Structure and Function: Cells - The Basis of Life

1/8/2008 12:00:00 AM

Earth's Changing Surface: Sculpting the Landscape

1/8/2008 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of three Science Objects in the Earth's Changing Surface SciPack. It explores the landforms we see on Earth today and the processes that create these landforms. Landforms are the result of a combination of constructive and destructive forces. The Earth processes we see today, including erosion and the movement of lithospheric plates, are similar to those that occurred in the past. Some changes in Earth's surface are abrupt such as earthquakes and volcanic eruptions. Other changes shaped in part by the motion of water and wind on weathered rock act over very long times to level mountain ranges and through sedimentation create new forms elsewhere.

Earth's Changing Surface: Humans as Agents of Change

1/8/2008 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of three Science Objects in the Earth's Changing Surface SciPack. It explores the natural and human influences on landscape evolution. These influences sometimes accelerate or slow down the process of landscape evolution. Human activities such as deforestation, accelerated global warming, and mining have impacted Earth's changing surface. These activities are not new processes but often increase or accentuate the natural processes. When natural processes are accelerated, humans are often affected by the changes in their environment.

Cell Structure and Function: The Molecular Machinery of Life

1/8/2008 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Cell Structure and Function SciPack. It explores cells at the molecular level. It is at the molecular level that many of the basic functions of organisms are carried out such as, protein synthesis, extraction of energy from food, and replication. All cells have similar types of complex molecules that are involved in these basic activities of life. These macromolecules include proteins, lipids, carbohydrates and nucleic acids, which interact in a soup, about 2/3 water, surrounded by a membrane that controls what can enter and leave the cell. Proteins act in several ways including enzymes that are responsible for catalyzing chemical actions, receptor molecules in the cell membrane, hormones that travel distances to communicate regulatory processes and structurally as the physical fibers of the cell. The cell's energy comes from food in the form of sugars or from stored fats (lipids). Lipids are also a critical component in the structure of the cell membrane. The cell membrane in association with carbohydrates and proteins, regulate the flow of water, ions, and other molecules into and out of the cells. Nucleic acids contain instructions for genes that determine structural and chemical processes through protein synthesis.

Earth's Changing Surface: Changing Earth From Within

1/8/2008 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of three Science Objects in the Earth's Changing Surface SciPack. It explores the landforms we see on Earth today and the processes that create these landforms. Landforms are the result of a combination of constructive and destructive forces. The Earth processes we see today, including erosion and the movement of lithospheric plates, are similar to those that occurred in the past. Some changes in Earth's surface are abrupt such as earthquakes and volcanic eruptions. Other changes shaped in part by the motion of water and wind on weathered rock act over very long times to level mountain ranges and through sedimentation create new forms elsewhere.

Science of Food Safety: Microbes, Friend or Foe

12/10/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Science of Food Safety SciPack. It explores how bacteria live in close concert with humans. Bacteria are masters at exploiting a variety of niches in the human body and live in huge colonies in places such as the skin, intestines and mouth. Most of these bacteria are harmless to the human body, and many are important in assisting its normal, healthy functioning. Disease in humans results when organisms such as bacteria interfere with the normal operation of the human body, most commonly foreign organisms entering the body. The human body has many mechanisms to protect itself against outside organisms that may interfere with its normal operation. Bacteria that gain entrance to the body may form colonies in preferred organs or tissues, emitting harmful toxins as waste products. If the body's immune system cannot suppress a bacterial infection, an antibacterial drug may be effective-at least against the types of bacteria it was designed to combat. Viruses invade healthy cells and cause them to synthesize more viruses, usually killing those cells in the process.

Earth, Sun, and Moon: Motion of the Moon

12/10/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Earth, Sun, and Moon SciPack. It provides an understanding of the moon's orbit around Earth and the phases of the moon as experienced from Earth's surface. The Moon orbits Earth approximately once per month, causing the pattern of moon phases. Although half of the Moon's surface is always illuminated by the Sun and half is always shaded, the portion of the illuminated surface that we see changes as the Moon orbits Earth.

Science of Food Safety: Growth and Reproduction of Cells

12/10/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object second of four Science Objects in the Food Science Safety SciPack. It explores cell functions involving chemical reactions that are made possible by protein catalysts called enzymes. These reactions require a fairly narrow range of temperature and pH. Low temperatures cause them to go too slowly, and high temperatures or acidity can change cell structures. Molecules from the environment may also attach to or pass through a cell's membrane and affect reaction rates. Cells such as bacteria require energy and nutrients from their environment for survival. When they grow to a certain size, bacteria can reproduce by creating a copy of their DNA and then splitting in two. Under optimal conditions, this doubling of bacteria and each of their generated offspring can proceed at a fast rate, expanding a bacterial colony rapidly in a short time. Many of the precautions taken to protect the health of humans focus on limiting the growth of bacterial colonies by creating environmental conditions not favorable for their functioning or reproduction. Variations in genetic information within a population of bacteria can permit some individuals to survive and reproduce more effectively than others in a given environment. Such hardier individuals usually represent only tiny fractions of a population, but their rapid reproduction can quickly give rise to large numbers of successful offspring. This process may give rise to bacterial strains able to survive under new conditions, such as strains with resistance to overused antibacterial drugs, or grant previously harmless bacteria the ability to cause disease.

Science of Food Safety: Food Safety and You

12/10/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects inthe Science of Food Safety SciPack. It explores the scientist involved with the development of germ theory and pasteurization, which brought about great changes in the safe handling of food and water, and improved sanitation measures that represent some of the greatest public health contributions to date. More recently, humans have instituted laws requiring the monitoring of air, soil, and water for microorganisms that pose a threat to human health. Such agricultural and food safety regulations represent social trade-offs that ensure the population's general welfare at the price of increased cost or lowered efficiency. In addition to these large-scale societal precautions, humans rely heavily on personal measures to limit the transmission of invasive organisms into their bodies. These measures include keeping hands and skin clean, avoiding contaminated foods and liquids, cleaning and separating food items properly during preparation, cooking food at high enough temperatures for proper lengths of time, and keeping the temperature of food sufficiently low at all times when it is not being prepared or consumed.

Earth, Sun, and Moon: Earth's Seasons

12/10/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects in the Earth, Sun, and Moon SciPack. It provides an understanding of why we have different seasons on Earth and why seasons vary from one location on Earth and another. The Sun is the major source of energy for phenomena on Earth's surface. The seasons are caused by the tilt of Earth's axis with respect to the plane of its orbit around the Sun. Because the angle and direction of tilt does not change as Earth orbits the Sun, during half of the year the north polar region tilts toward the Sun, resulting in increased heating (summer) and away from the Sun during the other half of the year, resulting in cooling (winter). The seasons are reversed in the Southern Hemisphere.

Cell Structure and Function: The Cellular Factory

12/10/2007 12:00:00 AM

Earth, Sun, and Moon: Our Moving Earth

12/10/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Earth, Sun, and Moon SciPack. It provides an understanding of how we know that Earth moves in a nearly circular orbit around the Sun once per year, so that we see different constellations at different times of the year. Earth rotates on its axis once per day, making it appear as though the Sun, the Moon, and the stars revolve around Earth each day. Evidence however, demonstrates that it is in fact, Earth that rotates on its axis as it orbits the Sun, just as other planets in our solar system.

Cell Structure and Function: The Most Important Molecule

12/10/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Cell Structure and Function SciPack. It explores protein molecules at a more in-depth level. The work of the cell is carried out by the many different types of molecules it assembles, mostly proteins. DNA is the blueprint that determines the order of amino acids for any given protein that differs somewhat with each species. Protein molecules are long, usually folded chains composed of combinations from 20 different kinds of amino acid molecules. The function of each protein depends on its specific sequence of amino acids and the shape the chain takes as a consequence of attractions between the chain's parts. The action of the proteins is catalyzed by a set of enzymes (also proteins). Some of the assembled molecules assist in replicating genetic information, repairing cell structures, helping other molecules to get in or out of the cell, and generally in catalyzing and regulating molecular interactions. In specialized cells, other protein molecules may carry oxygen, affect contraction, respond to outside stimuli, or provide material for hair, nails, and other body structures. In still other cells, assembled molecules may be exported to serve as hormones, antibodies, or digestive enzymes.

Science of Food Safety: Understanding the Cell's Importance

12/10/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Science of Food Safety SciPack. It explores self-replicating life forms, which are all composed of cells. Living cells contain similar types of complex molecules that support the basic activities of life. These molecules interact in a soup, composed of about 2/3 water, surrounded by a membrane that controls what can enter and leave the cell. Cells have particular structures for cell functions, protection, and in some cases the ability to move. A single living cell represents the smallest individual unit of life. Single-celled organisms vary in the complexity of their structure and the amount of genetic material they contain, and populate all environments on Earth in astounding numbers and types. Those with less genetic material and simpler structures are more numerous. Bacteria are one type of single-celled organism that have an interdependent relationship with humans.

Oceans Effect on Weather and Climate: Global Precipitation and Energy

3/28/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Ocean's Effect on Weather and Climate SciPack. It explores the distribution of water and energy on Earth. The cycling of water in and out of the atmosphere and oceans affects Earth's climates by influencing patterns of precipitation and by transferring energy between the oceans and the atmosphere. As water moves through the water cycle, it evaporates from Earth's surface, rises and cools, condenses into rain, snow, or ice, and falls back to the surface. The water falling on land collects in rivers and lakes, soil, and porous layers of rock, and much of it eventually flows back into the ocean. The water cycle connects the oceans to all of Earth's water reservoirs via evaporation and precipitation. The ocean loses thermal energy due to the evaporation of water. This energy transfer drives atmospheric circulation as water moves to the atmosphere as vapor and eventually condenses, releasing thermal energy to the surrounding air.

Oceans Effect on Climate and Weather: Global Circulation Patterns

3/28/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Ocean's Effect on Weather and Climate SciPack. It explores ocean circulation patterns and the effect oceans have on climate. Water in the oceans hold a lot of thermal energy (more than an equal amount of land). Throughout the ocean there is a global, interconnected circulation system that transfers this thermal energy across Earth. The shape of ocean basins and adjacent land masses influence the path of circulation. As ocean currents transfer thermal energy to various locations, the temperature of the atmosphere above the ocean is affected. For example, the condensation of water that has been evaporated from warm seas provides the energy for hurricanes and cyclones. When the pattern of thermal energy released into the atmosphere changes, global weather patterns are affected. An example of a large-scale change like this is the El Niño Southern Oscillation, which changes the pattern of thermal energy released into the atmosphere in the Pacific.

Oceans Effect on Weather and Climate: Changing Climate

3/28/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the fourth of four Science Objects in the Ocean's Effect on Weather and Climate SciPack. It explores how Earth's climate has changed in the past and how it may change in the future. Climate change may occur as a result of changes in Earth's surface, atmosphere, and oceans. Such changes may be abrupt (such as gas and dust from volcanic eruptions or asteroid impacts) or may occur over very long times (such as changes in landscape or increase in carbon dioxide levels in the atmosphere). Even relatively small changes in atmospheric or ocean content and/or temperature can have widespread effects on climate if the change lasts long enough. Since the industrial revolution, the concentration of greenhouse gases in the atmosphere has increased at an unprecedented rate. Though climate change and changes in the composition of the oceans and atmosphere are natural, present modifications far exceed natural rates.

Oceans Effect on Weather and Climate: Global Climate Patterns

3/28/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Ocean's Effect on Weather and Climate SciPack. It explores global weather and climate patterns, focusing on why different conditions exist in specific areas. Earth's weather patterns, which consist of different conditions of temperature, precipitation, humidity, wind, air pressure, and other atmospheric phenomena, result in various climate zones across the globe. Weather and climate are the result of the transfer of energy from the Sun at and near the surface of Earth. Solar radiation heats land masses, oceans, and air differently, resulting in the constant transfer of energy as energy is "balanced" across the globe. Transfer of thermal energy at the boundaries between the atmosphere, land masses, and the oceans-influenced by dynamic processes such as cloud cover and relatively static conditions such as the position of mountain ranges and oceans-results in layers of different temperatures and densities in both the ocean and atmosphere. The action of gravitational force on regions of different densities causes them to rise or fall, forming convection currents (cells). This circulation, influenced by the rotation of the earth, produces winds and ocean currents.

Coral Reef Ecosystems: Ecosystems in Crisis

3/28/2007 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the fourth of four Science Objects in the Coral Reef Ecosystems SciPack. It explores the natural and human causes of ecosystem stress. Human beings live near coral ecosystems and use them in a variety of ways. Increasing amounts of stress is brought on these ecosystems as humans continue to modify the surrounding environment as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening the stability and overall health of many coral reefs. Human activities may also exacerbate the impact of natural disturbances on coral reefs or compromise the ability of the reef to recover from events such as hurricanes, tsunamis, or disease.

Force and Motion: Newton's Third Law

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects in the Force and Motion SciPack. It provides a conceptual and real-world understanding of Newton's Third Law of Motion, addressing common misconceptions associated with this law. Whenever one object exerts a force on another, an equal amount of force is exerted back on it. These equal and opposite forces are exerted simultaneously on the objects involved.

Energy: Different Kinds of Energy

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Energy SciPack. It provides a conceptual and real-world understanding of the different types of energy. Energy can appear in many different forms, however all forms of energy can be broadly classified as one or a combination of two kinds: kinetic energy, which is the energy of motion; and potential energy, which depends on the relative position or shape of an object. Other kinds of energy include gravitational energy (the separation of mutually attracting masses), thermal energy (the disorderly motion of atoms or molecules), and chemical energy (the arrangement of atoms).

Solar System: Formation of Our Solar System

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the fourth of four Science Objects in the Solar System SciPack. It explores the hypothesis that the solar system coalesced out of a giant cloud of gas and debris left in the wake of exploding stars about five billion years ago. Everything in and on the earth, including living organisms, is made of the material from this cloud. As Earth and the other planets formed, the heavier elements fell to their centers. On planets closer to the Sun (the inner planets), the lightest elements and their compounds were mostly blown or boiled away by radiation from the newly formed sun. However, on the outer planets, the lighter substances still surround them as deep atmospheres of gas or as frozen solid layers.

Rock Cycle: Earth's Autobiography

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the fourth of four Science Objects in the Rocks SciPack. It investigates how geologists have used rocks to help determine the approximate age of the Earth and provide a timeline of how the Earth's surface and environments have changed over time. Scientists have tools to estimate the ages of rock and the overall time scale of the rock cycle. Some processes happen quickly and some happen slowly, but the oldest rocks indicate that the rock cycle has been recycling Earth's material continuously for roughly 4 billion years. The same processes have been at work throughout Earth's history, and therefore scientists can use the present to interpret the past. Observations of rock (textures, minerals, and fossils found within it) provides evidence of the environment and processes through which it formed, including the pressures, temperatures, and forces that created it.

Coral Reef Ecosystems: Interdependence

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Coral Reef Ecosystems SciPack. It explores the interdependent relationships between species in the coral reef ecosystem. All populations in the reef ecosystem are a part of and depend on a global food web (a connected set of food chains) through which energy flows in one direction, from the sun into organism and eventually dissipating into the environment as heat. This food web includes ocean plants, the animals that feed on them, and the animals that feed on those animals. Energy is transferred between organisms and their environment along the way. Energy concentration diminishes at each step. The cycles of life continue indefinitely because organisms decompose after death and return food materials to the environment.

Coral Reef Ecosystems: The Living Reef

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Coral Reef Ecosystems SciPack. It explores the unique and diverse ecosystem of the coral reef. Coral reefs are very complex systems that create one of the largest structures on Earth of biological origins. Thousands of coral species exist in oceans worldwide. Reef-building corals remain on the same spot of the sea floor through their entire lives and have developed reproductive, feeding, and social behaviors suited to their situation. As they grow, reefs provide structural habitats for hundreds to thousands of different organisms.

Universe: The Universe Beyond our Solar System

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the fourth of five Science Objects in the Universe SciPack. It explores the more unknown parts of the universe beyond our solar system and provides an understanding of where and how we fit into the universe as a whole. Astronomers have carefully measured the changing positions of stars, leading them to believe that the Sun is located about half-way out from the center of a disk-shaped galaxy of stars, part of which can be seen as a glowing band of light that spans the sky on a very clear night. Although our Sun is a single star, most stars exist in systems of two or more stars orbiting around one another and are arranged in huge star clusters. Galaxies are isolated collections of billions of gravitationally bound stars and immense clouds of gas and dust. Galaxies are, in turn, grouped into galaxy clusters and super-clusters. The universe contains many billions of galaxies separated by immense distances of mostly empty space. Some of these distant galaxies are so far away that their light takes several billion years to reach Earth. This means that here on Earth we are seeing them as they were that long ago.

Energy: Energy Transformations

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Energy SciPack. It provides a conceptual and real-world understanding of how energy is transferred, from object to object and from one form of energy to another. Although the various forms of energy appear different, each can be measured in a closed system. This makes it possible to keep track of how much of one form of energy is converted into another form. Most of what goes on in the universe-from exploding stars and biological growth to the operation of machines and the motion of people-involves some form of energy being transformed into another form. The law of conservation of energy states that whenever the amount of energy in one place (or form) decreases, the amount of energy in other places (or forms) increases by the same amount.

Solar System: Asteroids, Comets, and Meteorites

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Solar System SciPack. It provides an understanding of the bodies other than planets that exist in our solar system. There are many asteroids and meteoroids composed of rock orbiting the Sun. Occasionally, one of these bodies enters the Earth's atmosphere, glowing as they disintegrate from atmospheric friction. Those that do not completely burn up in the atmosphere may impact the ground. Other chunks of rock mixed with ice have such long and off-center orbits that they only periodically come very close to the Sun, where some of their surface material is boiled off by the Sun's radiation and pushed into a long illuminated tail that we see as a comet.

Energy: Thermal Energy, Heat, and Temperature

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Energy SciPack. It provides a conceptual and real-world understanding of the relationship between thermal energy, heat, and temperature. The thermal energy of a material consists of the disordered motion of its atoms or molecules. Thermal energy can be transferred through materials or from one material to another by conduction (the collisions of atoms), or across space by radiation. If the material is fluid, convection currents aid the transfer of thermal energy (convection). When thermal energy is transferred it is called heat. Temperature is a measure of the average kinetic energy of atoms and molecules in a material.

Plate Tectonics: Consequences of Plate Interactions

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the fourth of five Science Objects in the Plate Tectonic SciPack. It identifies the events that may occur and landscapes that form as a result of different plate interactions. The areas along plate margins are active. Plates pushing against one another can cause earthquakes, volcanoes, mountain formation, and very deep ocean trenches. Plates pulling apart from one another can cause smaller earthquakes, magma rising to the surface, volcanoes, and oceanic valleys and mountains from sea-floor spreading. Plates sliding past one another can cause earthquakes and rock deformation.

Rock Cycle: Categories by Process

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Rocks SciPack. It provides an introduction to what rocks are, how and where they form, and what we can tell about a rock's formation by making observations about its characteristics. Different rocks have different compositions (element and mineral assemblages) and textures (grain size, orientation, etc.) Important observations of rock include characteristics of both a sample of the rock and its larger geologic context and natural setting. Observations of rocks can tell us about the processes and the environment in which they formed. The major categories of Earth's rocks include igneous rock, sedimentary rock, and metamorphic rock.

Universe: How We Know What We Know

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of five Science Objects in the Universe SciPack. It explores the methods and tools used by astronomers to study the universe and the various objects that make up the known universe. What we know about the universe today is a result of increasingly sophisticated technologies that allow astronomers to capture and study incoming light from the universe across many different wavelengths of the electromagnetic spectrum, as well as use computers to analyze data. Astronomers study the position and motion of objects, as well as the color and intensity of the light coming from those objects. These observations help determine the distances of those objects, their composition, and the processes at work.

Gravity and Orbits: Orbits

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of three Science Objects in the Gravity and Orbits SciPack. It provides an understanding of how gravitational forces influence the motion of an object in orbit. When a force acts toward a single center, an object's forward motion and its motion toward that center can combine to create a curved path around the center. Gravity governs the motion of all objects in the solar system. The Sun's gravitational pull holds the Earth and other planets in their orbits, just as the planets' gravitational pull keeps their moons in orbit around them.

Force and Motion: Position and Motion

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Force and Motion SciPack. It provides an understanding of how changes in position and motion can affect the way objects move, focusing on constant motion (where the direction and speed remain the same) and acceleration (a change in motion due to a change in an object's direction or speed). The position of an object must be described relative to some other object while the motion of an object can be described by its direction and speed. Velocity is a measure of both an object's speed and its direction (and can be described by vectors).

Gravity and Orbits: Gravitational Force

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of three Science Objects in the Gravity and Orbits SciPack. It investigates the variables that influence gravitational forces acting on objects. Mass is a measure of the amount of matter that makes up an object (regardless of where that object is located) and weight is a measure of the gravitational force acting on an object. The strength of the gravitational force between masses is proportional to the product of the masses and inversely proportional to the square of the distance between them. Gravity will cause all objects at the same distance from Earth's surface to fall toward Earth with the same acceleration regardless of their mass.

Universe: The Sun as a Star

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of five Science Objects in the Universe SciPack. It provides an understanding of how our Sun compares to other stars in the universe. Analyzing the light from other stars and comparing it with light from our Sun has allowed us to determine that our Sun is a medium-size star. The Sun appears brighter than the other stars because it is many, many times closer to us. It takes about 8 minutes for light to travel from the Sun to Earth, but more than four years for light to travel from the Sun out to the next nearest star.

Universe: Birth, Life, and Death of Stars

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of five Science Objects in the Universe SciPack. It explores the life cycle of stars and the variables that determine eventual characteristics of stars. The formation of a star begins with an immense cloud, containing molecules of the lightest elements, collapses under the influence of gravity. The molecules in the cloud heat (up as the cloud becomes more dense) until light elements consistently fuse into heavier ones, producing large amounts of energy. Eventually, the most massive of stars explode, producing new clouds that contain heavier elements. These new clouds of material set the stage for the formation of other stars and planets, in a cycle that repeatedly continues even today. The speed of this process and ultimate fate of a star depends primarily on its initial mass. Stars can differ from each other in size, temperature, and age, but they all behave according to the same physical principles.

Rock Cycle: Environments of Formation

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Rocks SciPack. It provides an in-depth exploration of the conditions and environment required during the formation of igneous, sedimentary, and metamorphic rocks. Igneous rock forms from the cooling and crystallization of magma. Sometimes the magma reaches Earth's surface and cools quickly; sometimes it does not reach the surface and thus cools slowly. Rocks at Earth's surface are subjected to processes of weathering and erosion, producing sediments as they are broken down. Sedimentary rock is formed when sediments are buried and solidified through various processes. Sedimentary rock buried deep enough may be transformed into metamorphic rock or melted down to magma. Rock formed deep within the crust (either igneous or metamorphic) may be forced up again to become land surface and even mountains by the forces that drive the motion of Earth's plates. Subsequently, this new rock too will erode.

Earth, Sun, and Moon: General Characteristics of the Earth

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of five Science Objects in the Earth, Sun, and Moon SciPack. It provides an understanding of how the different spheres (atmosphere, lithosphere, and hydrosphere) of Earth interact and why each plays an important role in making Earth the only planet with the conditions necessary for life. Earth is approximately spherical in shape like all planets and stars. Earth is composed mostly of rock. Three-fourths of its surface is covered by a relatively thin layer of water (some of it frozen), and the entire planet is surrounded by a relatively thin blanket of air.

Plate Tectonics: Plate Interactions

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of five Science Objects in the Plate Tectonic SciPack. It identifies the events that may occur and landscapes that form as a result of different plate interactions. The areas along plate margins are active. Plates pushing against one another can cause earthquakes, volcanoes, mountain formation, and very deep ocean trenches. Plates pulling apart from one another can cause smaller earthquakes, magma rising to the surface, volcanoes, and oceanic valleys and mountains from sea-floor spreading. Plates sliding past one another can cause earthquakes and rock deformation.

Universe: The Origin and Evolution of the Universe

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the fifth of five Science Objects in the Universe SciPack. It provides understanding of how the universe formed, how it has changed over time, and how it continues to change today. The ‘big bang' theory of universe formation is supported by recent observations of the motion of galaxies, as well as observations of the energy left over from the formation of the universe. This evidence suggests that the origin of the universe occurred approximately 13.6 billion years ago, during a point in time when the state of the universe was much hotter and more dense. The fact that light seen from almost all distant galaxies has longer wavelengths than comparable light here on earth provides evidence that the whole universe has been expanding ever since the big bang (and continues to expand today).

Plate Tectonics: Plates

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of five Science Objects in the Plate Tectonics SciPack. It provides a conceptual understanding of what plates are and how they move, contributing to a constantly changing surface. The Earth's continents and ocean basins are made up of plates consisting of the crust and the upper part of the mantle. One plate can consist of both continental and oceanic crust. These plates move very slowly (an inch or so per year) on the hot, deformable layer of the mantle beneath them. The outward transfer of Earth's internal heat drives convection circulation in the mantle. This convection, together with gravitational pull on the plates themselves, causes the plates to move.

Coral Reef Ecosystems: The Abiotic Setting

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Coral Reef Ecosystems SciPack. It investigates the abiotic characteristics that affect the coral reef ecosystem. The number and kinds of organisms found along each reef depend on the physical conditions of the environment and resources available, including food, light, water quality, temperature, and other organisms living in the reef. If conditions change significantly due to changes in climate, loss of food sources, excessive predation, or loss of habitat, the health and stability of the ecosystem will be affected. Like many complex systems, coral ecosystems tend to have cyclic fluctuations around a state of rough equilibrium. In the long run, if conditions remain reasonably constant a coral ecosystem can be stable for hundreds of years.

Solar System: The Earth in Space

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Solar System SciPack. It provides an understanding of where Earth is located in space and explores evidence used by astronomers to place Earth at this location. Earth is a relatively small planet and the third from the Sun in our solar system. The Sun is the central and largest body in the solar system. Our still-growing knowledge of the solar system comes to us in part by direct observation from Earth, including the use of optical, radio, and x-ray telescopes that are sensitive to a broad spectrum of information coming to us from space; computers that can undertake increasingly complicated calculations, find patterns in data, and support or reject theories about the origins of the solar system; and space probes that send back detailed pictures and other data from distant planets.

Rock Cycle: Cycling

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Rocks SciPack. It explores the variables that contribute to rock transformation and the continuous processes of rock formation that constitute the rock cycle. The rock cycle provides an example of the transfer of energy and mass in the Earth system. Earth is a closed system containing essentially a fixed amount of each element. Movement of matter is driven by the Earth's internal and external sources of energy, and is often accompanied by changes in the physical and chemical properties of the matter. Minerals are made, dissolved, and remade-on the Earth's surface, in the oceans, and in the hot, high-pressure layers beneath the crust. The total amount of material stays the same as its forms change.

Plate Tectonics: Layered Earth

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of five Science Objects in the Plate Tectonics SciPack. It explores the characteristics of the various layers of the Earth, using the way waves travel through the different layers to illustrate the differences in each layer. The interior of the earth is hot, under high pressure from gravitational pull, and more dense than its rocky outer crust. The earth is layered with a relatively thin crust; hot, deformable mantle; liquid outer core; and solid, metallic, and dense inner core.

Solar System: A Look at the Planets

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Solar System SciPack. It explores the similarities and differences in the planets that make up our solar system. Each planet moves around the Sun in the same direction in a nearly circular orbit, though each planet has its own unique orbital period and speed. The planets vary in size, surface and atmospheric composition, and surface features. In orbit around the planets, we find a great variety of moons, flat rings of rock and ice debris, and/or artificial satellites. Features of many of the planets and their moons show evidence of formation and evolutionary processes similar to those that occur on Earth. These processes include earthquakes, lava flows, erosion, and changes in the atmosphere.

Plate Tectonics: Lines of Evidence

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the fifth of five Science Objects in the Plate Tectonics SciPack. It explores the physical, geographical, and geological evidence for the theory of continental drift and plate tectonics. Plate tectonics provide a unifying framework for understanding Earth processes and history, and is supported by many lines of evidence. Over geologic time, plates move across the globe creating different continents (and positions of continents).

Gravity and Orbits: Universal Gravitational

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of three Science Objects in the Gravity and Orbits SciPack. It provides an understanding of gravitational forces associated with all objects that have mass. Every object exerts a gravitational force on every other object. The force is hard to detect unless at least one of the objects has a lot of mass. Any two objects will exert an equal gravitational force (in opposite directions) on one another. Gravity is the force behind the falling rain and flowing rivers, and is responsible for pulling the matter that makes up planets and stars toward their centers to form spheres.

Energy: Useful and Not So Useful Energy

11/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the fourth of four Science Objects in the Energy SciPack. It provides a conceptual and real-world understanding of why energy in some forms can easily be used but in other forms is difficult to use. Energy transformations usually produce some heat, which is transferred to cooler places or objects in the surrounding area via radiation or conduction. In such interactions the number of atoms or molecules is very large and statistics dictate that they will end up with less order than that the initial state. Although just as much total energy remains, it is more widely distributed or spread out which means less can be done with it. This is because useful transfer of energy can be accomplished only when energy is concentrated (such as in falling water, in high-energy molecules in fuels and food, or in radiation from sources such as the intensely hot sun).

Force and Motion: Newton's First Law

1/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Force and Motion SciPack. It provides a conceptual and real-world understanding of Newton's First Law of Motion. All objects will maintain a constant speed and direction of motion unless an unbalanced outside force acts on it. When an unbalanced force acts on an object, its speed or direction (or both) will change. The tendency of objects to maintain a constant speed and direction of motion (velocity) in the absence of an unbalanced force is known as intertia. Even in the most familiar, every day situations, frictional forces can complicate the analysis of motion, although the basic principles still apply.

Force and Motion: Newton's Second Law

1/1/2006 12:00:00 AM

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Force and Motion SciPack. It provides a conceptual and real-world understanding of Newton's Second Law of Motion. An object's change in motion is proportional to the net force applied to the object and inversely proportional to the mass of the object (being the measure of its inertia). The magnitude of the change in motion can be calculated using the relationship F = ma, which is independent of the nature of the force acting on the object.