Starch
Starch is a type of sugar that plants make to store energy in foods like rice and potatoes.
A jar holds a stack of dried pasta — dozens of pieces packed tightly inside. Plants store starch the same way: small sugar units linked in long chains, packed into seeds or roots. Each piece of pasta is like one sugar unit. The jar holds them all until the plant needs energy.
Explaining starch by grade level
Plants make starch to save energy. Rice and potatoes hold a lot of starch. You can find hidden starch with iodine drops. The drops turn dark blue on starchy foods.
Projects that explore starch
Plants store energy as starch in foods like rice and potatoes. When iodine solution touches starch, it turns dark — a simple color change that reveals which foods hold this stored plant energy.
Apples hold some of their stored energy as starch, and that starch breaks down as apples ripen. Warmer storage temperatures speed up ripening, so you can track the change by testing starch levels with iodine spray at different temperatures. As storage temperature rises, starch decreases — and the longer apples stay in storage, the more pronounced that drop becomes.
Leaves are one of the places where plants build up starch to store energy. After removing a leaf and boiling it in alcohol to clear the green color, you add potassium iodide drops to reveal how much starch is inside. The darker the purple color, the more starch the leaf contains.