We started class with a couple of experiments about osmosis, diffusion, passive transport and active transport. First we opened a container of perfume. Students were asked to raise their hands when they could smell the perfume as it diffused through the room. We talked about molecules moving from areas of high concentration to areas of lower concentration. Then we had all the students move into a tight huddle at the front of the classroom. We talked about how they wanted to move further away from the huddle - just as the perfume molecules wanted to diffuse and move to an area of lower concentration.
Next we put a tea bag and sand in warm water. After 15 minutes we observed that that the tea - through passive transport had moved out of the tea bag, but the sand hadn't moved into the tea bag because there needed to be active transport, energy, to move the sand into the bag.
Our last experiment was putting 3/4 cup of water in two separate beakers. To one we added 15 grams of salt and a slice of potato. To the other we added only the slice of potato. After 20 minutes we took out the potato and noticed that osmosis caused the potato in the salt water to lose water, it was very bendable. The water in the potato left the potato to balance with the salt water. The potato in the plain water was still firm.
Veterans assembly is tomorrow at 10:40. Thursday morning will be picture retakes.
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