Hole-Y Walls

HOLE-Y WALLS

Another amazing talent plants have is the ability to absorb water right through their skin. This process is called osmosis, and you can do an experiment that shows how it works. QUESTION Can liquid really pass through walls?

MATERIALS

2 wide glasses or measuring cups Water Tincture of iodine (available at a drugstore) Cornstarch A small, sealable plastic bag

Procedure

hole-y walls

Hole-Y Walls Science Fair Project

Fill both glasses approximately three-quarters full of water. In one glass, mix two teaspoons of iodine with the water. In the other glass, mix one tablespoon of cornstarch with the water, and pour about half of it into the plastic bag. Seal the plastic bag and place it into the iodine mixture. You may need to wash the bag with water to make sure there is no cornstarch on the outside when you place it in the iodine. Allow the bag to sit in the iodine for an hour and observe the changes that occur during that time. Meanwhile, drop a few drops of iodine into the glass with cornstarch in it and observe what happens.

WHAT’S HAPPENING

The cornstarch mixture turns a dark color when iodine is present. This was proved when you dropped the iodine into the second glass. Iodine also turns color when in the presence of a starch.