Peanut Brittle Math - Volume verses Weight

We're getting ready to make peanut brittle tonight, but first I thought we'd do a quick Math Monday lesson, with the peanuts.

I showed the kids, that the recipe called for a pound of raw peanuts. Usually we buy our peanuts in bulk, but this year all the store had was prepackaged peanuts. So, I already knew each package was exactly one pound, but I didn't point that out to the children.

Instead, I asked them how many ounces are in a cup - 8 ounces.

And, how many ounces are in a pound - 16 ounces.

And, if 2 cups of peanuts would make a pound? They were pretty sure it was a trick question. Apparently, they had learned something about volume and weight from our snow experiment. They suspected they weren't interchangeable, but they weren't sure why.

So, we placed our old, clear, measuring cup on our scale, and zeroed the scale out (a lesson in itself).

The girls measured out two cups of peanuts, with our smaller one cup measure, pouring them into the bowl on the scale.

Two cups did not equal one pound.

In fact, it took three cups of peanuts to make a pound.

Finally, we talked about the difference between volume, and weight - how a fluid ounce, is not the same thing as an ounce used for weighing, and how it all becomes clearer by turning the measuring cup around to the metric side, where volume is measured in liters, and weight is measured in grams.

You can find more fun with math at this week's Math Monday link-up, over at Joyful Learner.

It's great to be a homeschooler.