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Home > Life Science > Independent vs. Dependent Variables
by Robin Fujioka, Sat Sep 24, 2011 1:23 PM
My students are still confused about the independent and dependent variables. We just completed their first control experiment and they are still confused about the two different variables. In fact, some students still think it's okay to have more than two variables in an experiment! Yesterday, we had a review session for their upcoming test, I asked them, if they were testing the amount of light needed to make flowers bloom, what would be the independent and dependent variables and what would be a good control for this experiment. Some students could answer correctly, but others had no idea. Any suggestions on how to overcome these misconceptions?

I tried using acronyms "DRY MIX", (dependent, responds, graph on y-axis) and (manipulated, independent, graph on x-axis), I drew pictures, we did the control experiment. But still, some are still confused. I'm open for any suggestions :-)
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by Chris Leverington, Sat Sep 24, 2011 3:10 PM
What grade do you teach. There are some good Simpsons and Spongebob worksheets out there for Independent vs Dependent Variables. I have found this a very difficult concept for students as well...especially when you throw controlled variables in there as well. I did a lot more bell work questions on these this year...and found that the repetition is good.

I also used the if,then hypothesis format as a tool. The "if" part of your hypothesis is the independent variable; the "then" part is the dependent. In your example, my hypothesis could be: If I increase the amount of time the flowers get light, then they will bloom in a shorter amount of time." The if part is your independent, the then part is your dependent.

A student said to me "Basically what you are doing is the independent, what you are trying to figure out is the dependent." and I said yes...and that seemed to help the kids as well.


I know its a tricky subject...but they need to understand it :) I put an independent/dependent variable question on every test through out the year, because there are a lot of those questions on the AIMS test in Arizona.
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by Michelle Amorin, Sat Sep 24, 2011 5:10 PM
Hi,

What I do at the beginning of the year is review scientific method and I spend a day on reviewing control, independent variable, and dependent variable. I've used the Simpson's worksheet with my student before. I usually do one with them and then have them do the rest on their own. I do find that the students still get confused about them.

To sum everything up, I have them do a mini lab called "Helicopter Lab." I adapted it from an elementary experiment for my high school kids. I just wanted a really fast, short activity for them to do. I went through the independent, dependent, control variables with them and they seemed to understand it.

I hope this helps.
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by Robin Fujioka, Sun Sep 25, 2011 11:07 AM
Hi Michelle and Chris: Thank you for your reply. I teach 10th graders. Thanks for reminding me about the Simpson worksheets, I used to do those with my 9th graders for Physical Science class. I've got to say at least half of the students get the concepts, however, I often wonder if the other half would focus and stop "spazzing" out, perhaps they would get it too. Teenagers....:-)
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by Michelle Lee, Sun Sep 25, 2011 8:21 PM

Hi Michelle and Chris

When I teach dependent and independent variables I tie them into graphing and data collection.
When my students are looking at an experiment I tell them to ask the following questions to determine the variables.
1. What is being tested in the experiment? or What is the problem the experiment is to answer? (This directs you to the independent variable?)

2. What are the results in the experiment? or What are the outcomes in the experiment?

I also use the following Acronym DRY MIX.
DRY MIX also helps students create a graph from the data collect in experiments.
D-Dependent variable
R- Responding variable
Y- (goes on) Y-axis

M-Manipulated variable
I-Independent variable
X-(goes on) X-axis
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by Kara Kitamura, Mon Sep 26, 2011 10:34 AM
I love the DRY MIX idea! It makes it simple to remember.
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by Catherine Hawkins, Mon Sep 26, 2011 11:53 AM
Ok - I am an educated woman and also a teacher - but at the elementary level - but I have to say that I NEVER had independent and dependent variables explained to me in any good way! I just learned a lot in this forum - the DRY MIX acronym is great! Thanks for the lesson!
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by Angelika Fairweather, Mon Sep 26, 2011 3:25 PM
I struggled for years helping my students get independent vs dependent variables. I then stumbled across this article Inquiry on Board . This article describes creating posters to help guide students through experimental design, selecting independent, dependent and control variables. After the initial lesson, I kept the posters up and used them throughout the year. The author's method really worked well for my students.
Thank You,
Angie
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by Maureen Stover, Thu Sep 29, 2011 3:01 PM
Hi Robin and other thread participants,

My students also have some difficultly distinguishing the difference between dependent and independent variables. Using acronyms, like "DRY MIX", is a great way to help your students remember key ideas. I learned the mnemonic "King Philip Came Over From Great Spain" for kingdom, phylum, class, order, family, genus, species in high school and I still use this quick rhyme to help my students remember the the order of scientific classification.

Chris mentioned that "repetition is good". I couldn't agree more. Giving our students opportunities to practice difficult concepts helps them to understand and internalize the concepts. The journal article Science Sampler: The Great Fakesperiment has 10 fake experiments that help students practice identifying dependent and independent variables.

Teaching kids to understand difficult topics is always a challenge for teachers. What are some of the strategies that educators use to help clarify difficult to understand topics?
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by Loren Nomura, Sat Oct 01, 2011 8:48 PM
For this, I just try constant repetition with the students. Indep. Variable is what you change on purpose and test in an experiment, dependent is what you are measuring. I also think acronyms are a great way to help kids memorize information.

I also have worksheets that I like to use to have students demonstrate how much they know as a constant formative assessment. Here are some resources.

Sorry I couldn't be much help but hopefully you can find something useful in the handouts.
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by Angelika Fairweather, Mon Oct 03, 2011 4:14 PM
Thank you for sharing those fantastic resources. Several threads suggested the key to helping students get a solid grasp on variables is by revisiting variables consistently throughout the year. I am always trying to figure out simple experiments that are great for assigning independent, dependent and control variables. What are some experiments you have tried in your classroom that work well for independent vs dependent variables?

My favorite is how much water can the different types of baby diapers hold.

Thank You,
Angie
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by Robin Fujioka, Tue Oct 04, 2011 1:35 PM
Aloha All: It is refreshing to read that we all have similar challenges on this topic. Kids will be kids no matter where they live. Acronyms and repetition seems to help most kids. Thank you to all who shared resources.
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by Loren Nomura, Fri Oct 07, 2011 5:20 AM
Well it depends on the quarter. Our school has us science teachers follow a compendium. Maybe you can use some of these ideas though to engage your students.

1st Quarter: we do grey water. We vary the amount of Dawn soap we give to radish plants and measure their growth over three weeks. You have the students mix the soap in with the water and then make five separate pots of plants with radish seeds in each (one for control or regular water, another with 25% soap water, 50%, 75% and 100%). You can establish the baseline for how much soap is in the 100% solution and then based on that make the other solutions (50% would be half of the soap water, half of pure water).

2nd Quarter: we do the egg osmosis lab. In this experiment we vary the liquid the egg is submerged in (vinegar, syrup, and water) and measure its mass (dependent variable). First phase (must be done in order) is we put the egg in vinegar (students note that the egg shell dissolves and the egg gains mass). Then in syrup (egg loses mass), then in water (egg gains mass). This is a cool experiment for cell transport and osmosis too!

3rd Quarter: rockets and motion. This one you need a lot of funding for though, since our school pays for it. Basically you calculate how far a rocket goes (using an altitude finder) and measure that as the dependent variable, the independent variable is the fuel type (how powerful the fuel is).

I think your best bet if you're going to do these experiments is the soap water experiment and also the egg osmosis one. Definitely way too advanced for elementary students (sorry!) - we use this for freshmen in high school.

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by Nicole Lofgren, Sun Oct 09, 2011 11:03 PM
Maybe actually have them run a lab where they are allowed to change more than one variable then ask them to explain what caused the results. When they can't explain it then you have your teaching moment, or if they try to pick one over the other you can ask how did they know it was x and not y.
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by Loren Nomura, Mon Oct 10, 2011 7:46 PM
Yeah I have tried that for science fair. Some of the students have a really difficult time identifying just one IV and DV so you can imagine how much harder it is for those students to have to work with possibly two IVs and how in turn the interaction between these IVs affects the DV. I usually try to just keep it as simple as possible but it is great to see that some students like to challenge themselves and just take things one step further to expand their knowledge.

For example, one student wanted to see if there was an interaction between type of soil (sand, regular dirty, no medium, rocks, etc) and water type because they had read that certain chemicals in water could erode or affect the type of soil, which may in turn cause a measurable interaction. I thought that was kind of cool.
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by Carolyn Mohr, Mon Oct 10, 2011 8:38 PM
Hi Robin and thread participants.
I, too, like to use the paper helicopter lab that Michelle provided. I have found students of all ages benefit from that simple experiment. I was just reading an article in the Learning Center entitled, "Line Graph Learning". Perhaps going from interpreting line graphs to the experiment instead of from the experiment to the graphing - might help some students make the connections and deepen their understanding of the relationship between independent and dependent variables. It is an excellent article about how to learn from line graphs.
Thanks for starting this discussion, Robin. I can't wait to hear more ideas on how to help our students understand these important terms.
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by Kathryn Kennedy, Tue Oct 11, 2011 6:53 PM
I made this powerpoint to use as a review for my upper level students. Feel free to use it or make adapt it for your classroom. If you make any corrections, please let me know so I can edit my original.

Cheers!
Kathryn
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by Robin Fujioka, Sat Oct 15, 2011 10:27 PM
Kathryn: Thank you for sharing your power point. Great examples included to help students understand the vocabulary. The scientific method is taught to students every year in each science class, however, students have a hard time with it.

I like your discussion about the hypothesis how it should not be a guess. Every year, I ask students the question, what is a hypothesis. Students always shout out "an educated guess". I always have to stress that their hypothesis got to be testable. I wonder where my student's idea that the hypothesis is "an educated guess" come from?
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by Kathryn Kennedy, Sun Oct 16, 2011 8:47 PM
Hi Robin -

Glad that you found the experimental design powerpoint useful! My students also consider a hypothesis to be an educated guess. This is something that will continue, I believe, for a very long time. We just need to stress to our students that as they become older, their terminology within science needs to be refined so the definitions that they are used to will ultimately be altered or become more specific. I call this science maturity; as students are able to grasp more complex ideas, we often have to change terminology to fully describe an idea or term.

I use the phrase 'tentative or possible explanation' for hypothesis in my classroom. Does anybody else have a different way of describing a hypothesis?
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by Kathryn Mattila, Sun Oct 16, 2011 10:19 PM
I just finished going over the scientific method with my 7th grade and 8th grade students. They are still struggling with the different kinds of variables. I love the DRY MIX idea. I think that will really help my students about the different variables and where they belong on the graph. I will introduce it next time we do our next lab.
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by Robin Fujioka, Sun Oct 16, 2011 11:29 PM
Kathryn K.

Science Maturity.....that's a great way to put it. I'm going to use it :-)
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by Loren Nomura, Mon Oct 17, 2011 3:41 AM
Here's another quiz on the scientific method I made last year. You can feel free to modify it as you need. It gives additional examples of identifying IV and DVs.
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by Sarah Topper, Wed Sep 05, 2012 4:09 PM
Thanks for all the great ideas. I found another article on the NSTA site that has some other great scenarios, http://learningcenter.nsta.org/files/ss0903_74.pdf

I am teaching my 6th graders these concepts as we go through our first few labs this year in order to get ready to start science fair and I want to make sure they really understand the variables before we start on their own experimental design.
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by Erin Mendelson, Tue Sep 11, 2012 2:41 AM
Hi Robin,
For some reasons, my students catch on to the concept of independent and dependent variables through this worksheet that uses SpongeBob SquarePants' analogies. It's catchy and challenging. I also use frequent formative assessments to continually reteach this concept. It takes my students about twenty different examples spread through out the unit to become fluent in identifying each variable. I suppose practice makes perfect.
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by Robin Fujioka, Thu Sep 13, 2012 2:13 AM
Sarah: Thank you for sending the article.

Erin: I couldn't open your Sponge Bob attachment, however, it must be similar to the one I used for my Physical Science kids a few years ago with the green slime on the shower and testing the shampoo on Lisa and her family. I remember the scenarios were pretty silly, but the kids actually go it. Thanks for reminding me about this worksheet, I need to remember to use it next year when talking about the difference between the control, independent and dependent variables....it always confuses the kids....even after doing a Control Lab Experiment.
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by Rochelle Tamiya, Sat Sep 15, 2012 11:19 PM
HI Robin!!

Not sure if this will help but I am a very visual learning, like my students so acronyms like the DRY MIX will be wonderful!! Also, I teach my students that the Independent Variable is usually the thing you are testing and the Dependent Variable is what you usually measure. I also tell them that the Independent variable is like the "cause" and the Dependent Variable is like the "effect".

For example, If plants require sunlight, then the growth of plants will increase with more exposure to the sun than plants that are in the shade.

Independent variable: sunlight
Dependent Variable: growth of plants

NOTE: sunlight (causes) plants to grow or not grow (an effect) ALSO,
growth of plants DEPENDS on the amount of sunlight...

Like every thing in life, there are exceptions, however, for the most part, my students can understand the concepts "independent" of each other by learning it this way. It took me a couple of years to get it straight myself (as I sit hear and contemplate if I am telling you the right thing...haha). Studied separately and in a worksheet, it seems easy, however, creating your own experiment and pointing these two out get confusing especially if there is more than one variable (I tell students too many variables will result in you not knowing what CAUSED the change that you are observing whether it be growth, time, speed, etc..).


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by Robin Fujioka, Sun Sep 16, 2012 3:38 AM
Hi Rochelle: After I teach the kids about independent and dependent variables, we do a Control Lab with Lima Bean seeds. We test just one variable and they want to add more than one variable like your students. It's interesting to see how students of different ages and from different places experience similar challenges.
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by Tina Shortouse, Mon Jan 21, 2013 10:56 AM
Hi... I am a parent. I have been trying to figure out what the independent variable and dependent variable... The DRY MIX was of no help to me as I do not understand it.. The if=independent and the then=dependent...as you state in your hypothesis. So, what you are doing is the independent and what you are trying to figure out is the dependent. This is all good and well now that I get it... BUT... my sons project is on Alphabetizing in Javascript.. So, what would be the independent? The program he creates? and what would be the dependent? The alphabetized list? This is listed in science buddies as intermediate... I do not even know how to display the results... any suggestions to all of the above?
by Michele Bloomquist, Mon Jan 21, 2013 3:04 PM
What student doesn't want to shine by showing off what they know? So I concluded the mystification of varaibles (independent and dependent) was more due to a lack of concept rather than knowledge. What my students didn't seem to realize was the role of numerical values in deciphering the independent and dependent variables in an experiment just like in a math equation using x and y coordinate values. In fact, they were startled to realize the connections between the two disciplines could be so close. So, rather than the "cream used" or type of cream used as the independent variable (both vaguely qualitative in nature), I made the amount of cream or quantitative value (x value) as the independent varaible. This measurable change was much clearer to them. We also claimed it was a value or variable which could be controlled by the experimenter- rather than becoming the measurable result or outcome (value of the y variable or dependent resulting from the changes in the independent variable). Sponge Bob is so elusive if you don't quantify his manipulations of the varaibles! In this new light almost everyone thought they understood the difference between independent and dependent variables (for the time being anyway). I even showed them a graph relating the controllable factor (x or independent) to the resulting values (y value or dependent varialbe or "outcome"). The amount of light a plant is exposed to is the controllable event (x or dependent variable) and the amount of growth of the plant (measured by height or diameter is the outcome or dependent variable).
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by Betty Paulsell, Tue Jan 22, 2013 9:24 AM
Tina,

I have an easy way to help students remember independent and dependent variables. Independent is what "I" (as in Independent) am experimenting with. Dependent variable "depends" and what resulted from the experiment.

As for what your son is doing. It does not have variables. Not all science projects have independent and dependent variables. What he is doing is an invention (which do not follow the "scientific method" using variables). It might also be considered engineering design depending on his initial thinking on the project.

I hope this helps. If not, please send me a private message and I will see if I can be of more help.
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by John Heneghan, Wed Jan 23, 2013 2:34 PM
These are some great resources. I especially like the mnemonic device DRY MIX.
by Carolyn Mohr, Wed Jan 23, 2013 6:50 PM
Hi Everyone,
There is another excellent thread on this same topic that has lots of great ideas as well. Feel free to see what others have shared on this topic at General Science and Teaching > Dependent/Independent/Controlled Variables
Carolyn
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by Devin Bowen, Wed Jan 23, 2013 10:18 PM
I've never heard of DRY MIX. Good one.
by Mitchell Miho, Wed Feb 06, 2013 9:36 PM
Robin,
Great question. I am teaching in the intermediate setting and my students also have a hard time grasping the concepts of variables. I'll even admit that i took me a while to understand it as well as being able to put them into the scientific process for labs and lab reports. The dry-mix and other resources that were shared on this forum are amazing and I will definitely give them another refresher on variables this week! With science there is so much to teach and to cover that I am finding it very difficult to be able to keep up with all the new knowledge, while making sure they were able to grasp the basics. Thanks for spawning this great source of information and reminding me that i need to check for their understanding on this topic once again.
by Osamu Ono, Fri Feb 22, 2013 9:20 PM
Independent variable and dependent variable can be pretty tough to teach to the kids... I always try to get them to think "Dependent variable depends on the independent variable. So if you change something, and something changes because of it, the thing you changed is the independent variable and what was changed because of it is the dependent variable."

There is a web site that sort of goes over practicing the scientific method step by step. The link is below.

http://msubbingscience.wikispaces.com/LS+1+-+Science+Investi...xperiments

This website provides powerpoints and sample worksheets that you can use to teach them the different parts of the scientific method and what's involved, such as In/dependent variables.

When I taught at a School in Hawaii that wasn't ranked high, myself and another teacher took a similiar step like this website, by breaking down the scientific method and everything involved in it. So for example, we would take notes in our Kornel Notes about the scientific method (observations, question, research, hypothesis design an experiment, test the experiment, etc...) and have the students make up a lab on the left side of the notebook as we cover the topic.

Eventually, we would get to the independent/dependent variable portion. When we get there, we define what they are and share some examples. Then we would use a worksheet like the one provided on this web site and have the students figure out the in/dependent variables. We would then assess the student understanding, then have the students find the independent/dependent variables in the lab that they are creating within the Kornel notes.

Doing it like this might take a while, but we found that most of the students would understand the difference between the two this way. It might be because they are using in the setting in which they are making their own experiment (so they are more interested in learning the vocabulary words involved in setting up an experiment). I hope this helped!
by Nicholas DePue, Mon Oct 07, 2013 9:21 AM
My students (high school bio) have been having difficulty with this as well. We did an extra credit exercise in class which seemed to help several of them, though my lower functioning students still had difficulty.

I had them all crumple a piece of paper into a ball, and I walked around with the recycling can. I said, "Everyone gets one shot. Five total baskets gets everyone one extra credit point. Ten total baskets gets everyone two extra credit points." They were really excited and just figured it was a game. After everyone took their shot, I asked for someone to repeat the rules back to me. One student (not even one of my best) raised his hand and said, "If we score five baskets, then we get one point. If we score ten baskets, then we get two points." Literally as soon as he said it there was a collective "Oohhhhhhh." I asked them what two things were subject to change in that little game. "Whether or not we made the basket and how many points we earned." And which one of those required the other one to happen? "We needed to make baskets in order to get points." So which depended upon the other? "Points depended upon baskets."

Like I said, there was still some confusion with the weaker students, but most seemed to understand it better after that exercise.
by Olukayode Banmeke, Wed Oct 09, 2013 8:52 PM
Woww...several excellent contributions! Never heard of DRY MIX though, such a good mnemonic!!!
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