You might homeschool if your kids go off into the backyard and look for caterpillars to grow into butterflies. Know how to feed them and what to do when they emerge from their cocoons. To be fair we have done this before but actually paid for the caterpillars. My kids got smart and found some for free in our backyard. It helps that we have a backyard with trees. Specifically citrus trees. My daughters, yes the girls not one of the gaggle of boys I have, found the caterpillars on our citrus trees. They are Giant Swallowtail Butterflies - some of the largest butterflies in North America.
If you are interested in doing this project yourself you can order a kit online or find your own caterpillars. If you do it yourself you will need a mesh enclosure for them to live in (ours was reused from when we ordered the kit), and you will need to research how to feed them both as a caterpillar and as a butterfly. Make sure you are getting the correct caterpillars or you could end up with a house full of moths or worse, worms and bird poop (some of these really do look like bird poop).
Which ever you choose, it is so worth it. Have fun bug hunting and be sure to post your own pictures if you get some to turn into butterflies!