I get so excited when spring rolls around. Ask my kids and they'll tell you I'm almost giddy when the trees green up and the flowers start blooming. January is my absolutely least favorite month of the year. The Christmas decorations come down, the trees look dead, no flowers, blech! Then the crocuses stick their heads up, then the daffodils, then the cherry trees and weeping willows and WAHOO!
Al's Garden Center sent out their spring magazine-thing, and it had a great idea in it. Take a 2 liter pop bottle and cut it in two about four inches from the bottom. Put potting soil in the bottom, plant some seeds (especially near the edges), and stick the two halves back together (top over bottom) and screw on the lid. Then tape it shut and watch it grow! You can spritz some water in the top if it looks dry. What a great terrarium! Your little ones can watch seeds sprout, especially the ones on the edges where you can actually see the roots go down. When the plants get big enough, you can plant them outside in the yard. Kids get so much satisfaction from watching something they planted grow successfully. Try one terrarium of flowers and one of vegetables.
Let me know how it turns out!