I love growing herbs! Propagating basil is really just as simple as cutting, stripping the lower leaves and keeping it in a water for a few weeks. Voila, a ready to plant basil and the mother plant will usually benefit from the trim.
Build Your Own $20 Outdoor Cob Oven: weekend projects
Composting idea: Worm Tower - Drill lots of holes in a pvc pipe. Bury all but 6 inches in garden. Place kitchen scraps in the hole. Worms will come in and eat and then transfer the "goodies" throughout the garden.
Growing vegetables from food waste is a great lesson for kids and also makes great science experiments Teach students how to regrow food and pick a food to regrow as a class. Could use a food from a students leftover lunch.
Building Healthy Soil - Simple soil test and how to upgrade your soil structure. Fill quart jar full of topsoil and add water to almost full. Shake to dissolve clumps & let jar sit overnight to determine soil structure and how to improve it.