Plant tropisms: phototropism, hydrotropism, gravitropism

Integrated ScienceLife ProcessesAges 12–13

A bean plant grows in a pot: the shoot and root lengthen day by day. Drag the light source (or the water source) left and right and watch the shoot bend toward the stimulus after a few days, while the root bends the opposite way. Switch the stimulus type to compare phototropism, hydrotropism, gravitropism (lay the pot on its side), and the thigmotropism of a tendril. The stem's angle from vertical is measured and updates continuously.