Project: Osmosis and a Permeable Membrane

Everyone has a different background. My degree just happens to be in Molecular Biology, so I have a lot of sciencey stuff going on in my head all the time. That makes it easier for me to spontaneously unschool in science than in history or art. Those are the two subjects I probably have the least breadth or depth.

(The best part of homeschooling is that I’m slowly fixing that over time as I learn with my kids!)

Anyway, I can throw together a short unit study in anything in science almost accidentally, and I thought I’d share an adventure in membranes and osmosis from a few weeks ago.

First, my son read the beginning of The Way We Work, a lovely illustrated book about the biology of people. It touches on the chemistry and physics you need to know to understand how biology happens. It’s funny, it’s whimsical, and it covers a vast amount of molecular and cell biology, plus anatomy, reproduction, and I can’t remember what else.

I introduced it because I thought it was time he knew some more details about biology, and the large cartoony (and silly!) illustrations might be able to hold his attention. He uses some pretty weird but amazing visual metaphors. I had my son read a few pages while his sisters finished their math work, and then had him tell us a few facts he learned, just to check to see if he had paid any attention to what he was reading.

As it turns out, those first pages are about atoms, ions, and diffusion (among other things).

A few days later, he just happened to show up in my home office, bored. I didn’t have time to amuse him or do anything long and involved, so I just showed him where the dialysis tubing was in the science area of the homeschooling room, I gave him a vague idea of what to do with it and sent him a youtube video of how to use the dialysis tubing.

After he turned his hands blue, he came back up to my office, so I sent him off to watch the Crash Course video about Membranes and Transport (CC Biology #5).

Then he came back again. He hadn’t watched the video and got discouraged that nothing had happened to his experiment after five minutes. (Oops. I forgot to set his expectations for how long it would take).

We had a quick talk about what force was going to be moving his dye around, and he realized it was diffusion. I pointed out that even without the membrane, in five minutes the dye wouldn’t spread out. So now he’s off to go make his experiment again, this time with a control. He’ll have a second cup/beaker with no membrane — just dye and water. That way he’ll know if he should have expected anything to happen, or not.

He can watch the Crash Course video while he waits, then try out this PhET Membrane Channel Simutaion. It lets you play with a few particles and some different types of channel proteins.

But in reality, what actually happened is instead of re-doing the experiment, he played with the simulator. Then a friend logged on to Steam and they started up a game of StarCraft. Things happen.

I guess tomorrow he can set the experiment up again. And if he’s still bored after that… well, it’s spring. It’s a great time to scoop some organisms out of the now-thawed lake and look at them under the microscope.

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