Sprout grass or cereal grain seeds. When the sprouts are two to three centimetres high, use a fine tip pen with permanent ink to mark from the tip of the shoot every 2 mm interval back to the base of the shoot. Observe the relative spacings of the marks for the next several days as the plants grow. Extend this activity by developing a growth chart for students in the class. Let them search for similarities and differences between the rate at which they are growing and the rate at which plants grow.
Growth occurs near the tips.
Why this occurs is a fascinating subject in itself. The mechanism responsible for this is complex, and is based on the production of hormones by the cells. Research is being conducted to determine how genes influence cell growth and differentiation. The activity is designed to provoke the students' curiosity about an interesting problem. Some may revisit this topic at a more advanced level.