These are the two designs I came up with for the kids' t-shirts but didn't get to use. If anyone is interested, you're welcome to take them and use them. Please link back to me if you do! I found a few great tutorials to learn how to make these in photoshop. Here are the links:
Creating a custom shape and Fitting text to your shape
tutorial. The words surrounding the earth are from Jane Yolen's Earth Day poem.