Here's a fun activity you can do with any age.
Go through that box of old crayons and pick out all the blue and green stubs. Have your preschooler separate them to sharpen their comparison skills. Cut up the longer crayon pieces so that they are about lima bean size.
Put some paper muffin cups into muffin tins. We used little ones because we didn't have many crayon bits. Fill the paper liners with the crayon stubs. Make sure you put the green ones in first so that you can make some realistic looking continents.
Bake in the oven at about 300 degrees F for as long as it takes to dress a 3 year old, brush your teeth and fill a sippee cup. In laymen's terms, about 5-10 minutes. Don't over bake them! They need to melt completely, but not get soupy. If they get soupy, the colours won't stay separate. Let them cool completely, and peel the liner off.
And there you have it...little baby Earths!
Happy Earth Day!