Make beef jerky
A tasty lesson about how important water is in living organisms.
The fact that the human body is 70% water is pretty well known, but really on its own it's just a simple factoid. It doesn't teach you much. Instead, make the knowledge part of a lesson in biology revolving around the importance of water to (all!) life.
Since practical lessons tend to stick much better, this lesson uses all of the senses and lets the children get involved with the proces to make sure it sticks.
Observing ordinary meat
Start by getting a slab of ordinary meat to make jerky from. Show it to the kids; talk a bit about how water is important to living things. Let them handle the meat and ask them to write down what it looks, feels and smells like.
Next, tell them you're going to remove the water from the meat. (Don't tell them it becomes jerky, that might make them cheat in the next steps) Let them predict how much of the meat is water (their own best guess) and write it down. Also let them predict what will happen to the meat, using the same descriptors as in the first step (looks, feels, smells).
End lesson, make jerky
End the first part of the lesson. Use a very bland marinade to prep the jerky and then weigh the end result and write down the number. The reason for using a bland marinade is that you want to change the smell as little as possible! You can let the kid watch in on this part and/or turn it into another lesson, of course.
Prepare next lesson
Once the jerky is complete, start the next lesson. Tell the kids the total weight at the start. Then, let them weigh the end result and let them figure out how much of the initial weight was water that has now been removed.
Let them handle the meat again and write down the look, feel, smell, etc. Recover the earlier writings. Compare their predictions (both in water content % vs real and the predicted look/feel/smell vs the actual) and discuss the results. Then talk a bit about what has happened to the meat and where the differences are coming from.
Take questions, if any remain. Then, eat the jerky together.
- letting kids explore the proces with all their senses means things will stick better
- teaches children about the scientific method; make predictions, do experiments, see if you were right, figure out what happened
- learn about how things are prepared and that food isn't just produced in a factory
- material might be expensive and can only be used once
- lesson is split in two parts due to preperation proces of jerky
- not suitable for vegetarians (but try dried fruit instead; works about the same although it's a little further removed from the feel of human flesh)