This science experiment for kids explores plant growth and teaches students about root systems by growing beans on cotton balls.

Materials:

• Glass jar or bottle
• Cotton wool balls/wads
• Dried beans

Instructions:

• Discuss what plants need to grow, the purpose of leaves and how plants absorb water. Students can also explore plant life cycles and root systems.
• Stuff cotton wool balls into the glass jar.
• Then, stick one bean on either side of the jar in order to watch two beans growing at once.
• Water it until the cotton wool is damp but not too wet, and place the jar in the window.
• What happens after three days? One week? Two weeks? Have students observe, measure and record the beans growth over time.

Source: http://theimaginationtree.com/2012/04/growing-beans-on-cotton-balls.html