The effect of light on the growth of stems
(a) Plant some seeds that grow rapidly like as oats, radish, bean or mustard seeds in two flower pots. When the seedlings are about 2.5 cm high, cover single pot with a box that has a hole cut near the top. From time to time lift the box and view the direction of growth. Turn the box so that light comes from a dissimilar direction and observe again after a few days.
(b) Put two light baffles in a long, narrow box as shown in the diagram, and cut a hole in the end. Plant a sprouting potato in a small pot that will fit in the box. Place the pot behind the farthest baffle from the hole. Cover the box and place in a window. View the direction of growth from time to time.