Sat Dec 15, 2012 11:47 AM
This SciGuide is about the properties of matter (both chemical and physical), and how those properties can change. I enjoy this SciGuide because it includes a lot of activities that expressly addresses density which is a profoundly important concept when dealing with ocean chemistry: hot liquids (which are less dense) can contain more dissolved gases (like carbon dioxide, which plays a significant role in ocean acidification), cold liquids (which is more dense) contains more nutrients. Moreover, density lays the foundation for how convection currents work in the mantle as well as wind and ocean currents. It was its focus on density that drew me to it, I especially like the layered salt-water column in a straw activity. However, I’m not too big of a fan of the old :density of differently sized objects of different masses” activity that it has. Outside of being the standard go-to to teach density, my biggest problem with this is that it doesn’t really get to the fundamental concepts of how density works with matter. It stays at the surface Size = volume. Mass = grams of an object. That’s true, but what about fluids, which can have more matter stuffed into a given volume. Matter you can’t see, and isn’t expressly obvious as a steel ball versus a lead one. It also annoys me that it ignores how volume of an object changes based on its temperature which in turn changes its density. This is the very reason why water is so precious to life on Earth. However, this SciGuide did convince me that I should include density as part of my instruction.
The water column in a straw is a wonderful activity, though. It helps students realize that density of a liquid can change when material is added to the liquid (like salt). The volume of the liquid changes when temperature is change, thus resulting in a changed density (my own addition to the experiment). Another key chemical connection, is that dissolving salt in water is possible because both are polar compounds. But, water can only hold so much, which leads to supersaturation, crystal formation, metamorphic rocks, and sedimentary rocks.
The other activities are simply outstanding and should be included in any middle school science class just out of principle. They provide concrete experiences for key concepts that any student should understand regardless of their future plans.
Wed Nov 07, 2012 1:37 PM
A Rainbow of Stars!
This SciGuide is pretty nifty because it gives guidance on how to make something so abstract and invisible as light more real and relevant to our students. The EM spectrum is always a bit challenging for middle school students. They can't see it; they can't touch it; they don't think they experience it; and, they have a very hard time understanding that there's a link between magnets and electricity and that they BOTH release energy in the form of waves (called the EM spectrum) and that these waves all have different properties based on their wavelength and frequency. All of this is very abstract and usually involves math and scary greek letters. Then, ask them to understand that light behaves like a wave AND a particle and you've lost them!
This SciGuide does all of that. It starts with explaining how light behaves as a wave and a particle, then goes into its characteristics and color, and then finally deals with the full EM spectrum. By using demonstrations, worksheets, and labs, this SciGuides sheds more light on the nature of light for our students.
Wed Nov 07, 2012 1:21 PM
Where My Food Comes From!
I really like this SciGuide. I'm teaching an aquaponics class and food safety is a big issue for us. We're trying very hard to become certified as food safe so that we can sell and donate our produce. It's a challenge, but we really believe in our goals. The biggest problem I have as an educator is providing examples to my students for what food safety looks like. It's a challenge because they're so young (middle school students) and I'm not really the most knowledgable about it myself. But, this SciGuide really lays it all out on the table (literally). It has students explore the different hands that touch their food and discover the major sources for food-born pathogens. From this unit, I can have my student analyze our OWN 'farm' and have them come up with solutions to our problems, and take more ownership of the process! Awesome SciGuide!