Wednesday, April 10, 2019

Homeschool Science: The Gummy Bear Osmosis Experiment

Osmosis is such an important concept to understand when you're learning cell biology (see also: diffusion and active and passive transport!). Nothing about cells is going to make sense if you don't completely understand the ways that cells can communicate and exchange, you know?

The other day, looking for something--ANYTHING!!!--to engage Syd, who has been on more-or-less of a homeschool strike for a while now (middle school, amiright?!?), I hit on the idea of reviewing cell transport while playing with Syd's absolute most favorite thing in the world:

Gummy bears.

Friends, this project was a Big. Hit. Hallefreakinlujah!

So here's the scenario for gummy bear osmosis: the lipid bilayer of a cell membrane is semipermeable, so small molecules, like water, can pass through, but large molecules, and the cell's organelles, cannot. In the process of making a gummy bear, collagen is heated and then cooled, which causes it to form strong chains that act similarly to that cell membrane.

Osmosis is the process that describes the way that water wants to make solutions on both sides of a semipermeable membrane equally diluted. It's an easy way to make one of the processes of cell transport visible to the naked eye, which is why osmosis is what we mostly play with.

To demonstrate and measure osmosis in gummy bears, you need lots of gummy bears, a way to way and measure them, clean containers, and some different solutions to test. The idea is that you weigh and measure a gummy bear, put it in an interesting solution for a while, then way and measure it again to determine how much water it took in via osmosis.

The fun part is that you get to play with whatever solutions you think would be a good idea!

And Syd had plenty of good ideas!

She admitted that she knew what would happen with this one...

...and she was correct. Blech!

Syd also tested tap water--

--canola oil--

--dish soap--

--and several others, including vinegar, salt water, and water with baking soda dissolved in it:

Yeah, those are dirty dishes in the background. No, we don't wash them. I could be snotty and tell you that we do stuff like this instead, but actually we're just lazy and we'd rather read than clean. 
I did not require Syd to write her process as a formal lab procedure (we've done that before so that they know what it is, but this experiment is "just for fun," which is the lie that I told to get Syd to do science with me at all), but I did require her to write everything down, because, as I tell the kids all the time, writing everything down is what makes it into science!

However, if you want to have your kid write a formal lab procedure, or at least read one, here is a stellar write-up of a gummy bear osmosis experiment.

Syd weighed every single gummy bear by grams first, then weighed each one again after 2, 4, 6, 12, 24, and 48 hours. She also played with them, of course, because their textures get VERY interesting:

I won't tell you any of her results, because it's more fun if YOU do the project yourself, but here are some of the pretty photos that I took of her squishy gummy bear experimental subjects:

This one is my favorite. Its little face!

Yummy, right?

I won't go into it here, but Syd conducted this experiment as a prerequisite to an engineering challenge in which we dissolved the eggshells off of a couple of eggs, and then I challenged the kids to find a solution that served to remove the water FROM an egg via osmosis.

I'll show you the pics later, but it's harder than you think! Good thing that Syd took good notes about the results of her gummy bear osmosis experiment.

Or DID she?

If you're looking for a cell transport experiment with less of a time (and countertop space!) commitment, a few years ago we did this diffusion into gelatin experiment, and it was SUPER cool.

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