Teach the children about the life cycle of plants by reading books, playing videos or drawing pictures on the chalk board. Talk about how plants grow from nutrients in the soil, water and sunlight. You may want to read stories such as "From Seed to Plant" by Gail Gibbons or "Rosie Plants a Radish" by Kate Petty.
Give each child a ceramic pot that is about 4 or 5 inches deep and help them decorate it. The kids can paint the pots any color they like, then add flowers, animals or other designs. They can also glue charms or other decorations on the pot.
Pour potting mix in each pot until it's nearly full.
Instruct the children to plant their seeds 1 inch deep in the potting mix. Flowers such as aster or cornflower or small vegetable plants such as peas work well for this project.
Place the pots on a window sill and instruct the kids to water the plants with 1 to 2 inches of water during the school week. Add more water if the soil becomes too dry in between watering, but avoid over-saturating. Germination times very greatly depending on the plant. Many plants reach full maturity between 50 and 80 days. Allow the children to take their plants home at different times, depending on when the plant is ready.