Charissa is only three, but it's never to early to start learning. I know this is a very common idea, but I want to encourage you to start growing something with your child, if you haven't already. This flower box and potting soil where here when we arrived and a friend gave me some lettuce seeds. Check out Goodwill or garage sales to find a flowerbox - they are much cheaper that way!
This is a super easy project and produces tangible results. I will bring them indoors once it gets to cold and it will (hopefully) help to put fresh, green lettuce on our table throughout the winter months. I'll have a light on them during the darker hours. I planted one length of the box and then, three weeks later, sowed a second length. That way, we will have a "staggered crop" of fresh salad for an extended period of time.
Charissa remembers to water them far more faithfully than I do. This age is so wonderful - they learn without even knowing it!