Choose seeds that germinate easily when planting seeds with kids. Lima bean or marigold seeds are easy for children to handle, and they germinate with little effort.
Direct each child to fill a clear plastic cup, 3/4 full with sterile potting soil. Clear plastic cups between 8 and 12 oz. should suffice. Each child will require one plastic cup for each type of seed used for the project.
Ask each kid to press one seed down into the soil of each cup. Most seeds require planting at a depth of 1/4 inch. Each child should pat the soil over the top of each seed.
Mist the potting soil with water from a spray bottle. Fill a 12-oz. spray bottle with water and allow children to spray their planted seeds with the water until the soil is moist to a depth of 1 inch.
Set the plastic cups on a sunny windowsill. Check the plastic cups daily for seed germination, which should take between seven and 10 days. Maintain moist soil throughout the growing process, as well as at least six hours of sunlight per day.