Next, we set up our “Ready, Set, Melt” demonstration lab. Being that we live in South Florida, we do not have much experience with snow, so we did discuss how we have seen on the news, trucks up north driving down the roads after snow storms shooting out salt onto the snow covered streets. Some students had no idea what we were talking about, while others had actually experienced it while visiting up north. After our discussion, we set up three clear cups, one small ice cube in each cup and three timers. Students wrote these items on the inside flap of “Constant Variable” in their flap book. We followed that by adding the 2 tablespoons of sugar to cup number two, 2 tablespoons of salt to cup number three, and documenting it in our flap book under “Independent Variable.” We started our timers, and were ready to observe.
I explained to the students that “I, the Scientist,” change one variable. Hence, “Independent” starts with “I.” I found this was an easy little trick that helped them remember what the “Independent Variable” was. As we waited, and watched, we worked on a “Science Variables” worksheet. This worksheet contains 3 different illustrations with labels. We started off by circling the Independent Variable. The ONE thing I, the scientist, changed in the experiment. We then wrote down the other variables that we could see in the experiment under Constant Variable. We went on to discuss the Dependent Variable, the measurable result that we would get at the end of the experiment. Students realized it would have to do with time since there was a timer in the illustration. After some discussion, they realized it would be how long it took for the bead to fall off of the spoon.
At this point we went back to our demonstration. In both of my classes, the ice with the salt melted in half the time the others did. It took about 18-19 minutes for the ice cube to melt with the salt in it. You could hear the oh’s and ah’s.
As a review next week, I will be sending how a worksheet with a scenario, and students will have write down the constant, independent and dependent variables. As an assessment, the students will be doing a cut and paste activity where they will match the terms with the definitions and examples.
Your Thrifty Co-Teacher,