Osmosis in Potato Strips

An adult should cut the potato into strips — this experiment involves a knife and a raw vegetable that needs to be cut into uniform pieces.

Disposal: Potato strips and salt water can go in normal food/organic waste, not down a drain if it might clog it — check local guidance.

Do not start this experiment until an adult who has read the supervision notes above is present.

Materials

• A raw potato
• A knife and chopping board
• Two cups or glasses
• Salt
• Water
• A ruler

Steps

1. An adult cuts the potato into several strips of a similar size, and measure/record each strip's starting length.
2. Fill one cup with plain water and the other with water mixed with a generous amount of salt dissolved in.
3. Place potato strips into each cup and leave them for at least an hour (longer, such as overnight, shows a clearer result).
4. Remove the strips and measure their length and firmness again, comparing the plain-water strips to the salt-water strips.
5. Discuss why the strips in salt water became limp (water left the potato cells) while the strips in plain water stayed firm or grew slightly (water entered the potato cells).