What experiment can be done to prove that light is needed for the formation of starch in a leaf?

Place the plant in a dark place to drain the starch from the leaves for 2-3 days. Then expose to bright sunlight, covering part of the leaf with dense material from the light, water abundantly. After 2-3 days, cut off the leaf, place it in hot water and boil for several minutes. Then put in hot alcohol to draw the chlorophyll out of the leaf. After that, place the leaf in an iodine solution – the unclosed part of the leaf will turn blue, but the closed part will not. The starch turns blue under the influence of iodine – the place that was in the dark is not colored.