This project is quite affordable if you have a large classroom. This planting kit can be found at your local Target in the dollar section. The one photographed is of clover and if it is planted the first of March, you can have clover grown in time for Saint Patrick's Day.
Supplies: plant kit, a plastic spoon per child, a bowl per child, and water
Process: Plant your pot according to kit instructions
Teach Well: Giving your children a spoon and a bowl to plant their own pot gives them ownership over the plant. Make sure to water daily. The small pots dry out quickly and can not go a day without water.