Sprouted potatoes are fun for kids to grow and watch. Figure A Figure B Charlie Nardozzi of the National Gardening Association has some great ideas to help get kids interested in gardening. The National Gardening Association's Growing Ideas catalog, designed for use by parents and teachers, includes all sorts of ideas and projects to help you get started in gardening with kids. In three or four weeks a citrus tree will sprout from the soil.
Potatoes are easy to grow too.
Take an old potato that's begun to sprout in the pantry, and cut off a few inches of the sprouted end. Stick some toothpicks in the potato to support it over a glass jar filled of water. Place the cut side down in the water, and put the jar in a sunny location. The next thing you know, potato vines will have sprouted. Make sure the water level doesn't dip below the cut end of the potato.