I love working with food whenever I can in my science classroom. And I especially like using candy. You pull out a single M&M, and all eyes are on you. When you tell them they will be using any type of candy to do a lab experiment, they can’t wait to get started. Obviously, the first question I get is “Can we eat this?” Now, I’ve taught middle school students awhile now so I am extremely aware of the fact that even if I say “No,” students will still sneak in a lick or nibble! I’ve learned to keep a few extra samples of whatever food I’m using so at the end of class, students can get their candy fix!
In my seventh grade class, we have been discussing cells and how materials move in and out of the cell membrane through passive transport. This leads to discussing the concepts of diffusion and osmosis. When I found a lab that used candy to demonstrate the concept of osmosis, I knew it was a winner! I have been using a lab I found on this blog which is site that has many other resources and great ideas for teaching science. The link to the pdf file which I have used and adapted from year to year is linked below.
The lab must be done in two days. First, students will take a gummy bear and measure the height, width and mass. Next, the gummy bear is placed in a beaker of distilled water overnight. It’s always amusing to hear the predictions of what will happen. Without fail, I get at least one prediction of “It’s gonna explode!” What is it with science class and students’ expectations of exploding objects??
The students come in super excited to check out their bear the next day. Of course, half the groups have named their little gelatin blobs and are thrilled/mortified to see that their gummy babies grew overnight! Students check the height, mass and width again and find the percent change. (Always love the math tie in!) A graph is made and written responses are required. Then at least one student in every group tries to slurp down the bear or the water left behind. Disgusting, but amusing. (And don’t worry, I do not promote this, but it’s not worth fighting. I just make sure the beakers are clean and safe!)
While groups are working, I try to connect with them to see why they think the gummy bear grew to the size it did. Most students have no issue seeing the connection to osmosis! (Let’s be honest… there are always one or two that still remain oblivious to the fact that we science teachers DO have reasons for activities we choose to do in the classroom!) Other questions that can be used to dig deeper are:
“If we left the gummy bear in the beaker another night, would it continue to grow even bigger?”
“What might happen if the bear was left in salt water?”
“How might we make this process faster or slower?”
If you were to do a little google search on Gummy Bear Osmosis you can find many ideas and variations of how this may work in your classroom! This is the lab I’ve used and I encourage you to use it and check out the science blog here too! Thanks to “Mr. Poach” for creating this awesome lab packet! Happy diffusing!!