I thought your young gardeners would enjoy an gardening adventure, growing the TickleMe Plant (Mimosa pudica). Recently featured by the National Gardening Association, http://www.kidsgardeningstore.com/14-1030.html
If you want to give your young gardeners an experience they will never forget, consider having them grow a TickleMe Plant. This is the plant that will close its leaves and lower its branches when you tickle it. They sprout in days and can be grown indoors any time of year. Just Google TickleMe Plants or go to http://www.TickleMePlant.com for information seeds and growing kits. This plant has turned many kids into plant and nature lovers. I know, because I grow TickleMe Plants in my classroom.
Happy Growing Martha