Rain and Water Runoff Experiment

A large watering can filled with water

Four identical containers for measuring water amounts (large cups or jugs)

Four test surfaces — a patch of grass, bare soil, concrete/pavement, mulch or wood chips

Trays or shallow containers to catch runoff

A timer

A notebook for recording results

Set up four stations, each on a different surface: grass, bare soil, concrete, and mulch. If you don't have all four, pick any three that are available.

Before the experiment, ask your child to predict: "Which surface do you think will absorb the most water? Which will have the most runoff?" Write down predictions.

Measure out exactly the same amount of water for each station — one full watering can per surface is a good amount.

Pour the water from the same height onto each surface. Do them one at a time so you can observe each carefully. Start the timer.

Watch. Grass absorbs steadily. Soil absorbs but may puddle. Concrete runs off immediately. Mulch soaks up water like a sponge. Time how long each surface takes to either absorb the water or create runoff.

Compare results to predictions. "Concrete had the most runoff because it doesn't absorb. Mulch and grass absorbed the most. That's why gardens and parks matter in cities — they soak up rain."

This is a genuine environmental science experiment. Engineers and city planners study these exact dynamics when designing stormwater systems.

Connect it to your neighborhood. "When it rains hard, where do you see puddles? Where does water drain?" Drive the concepts into the real world.

Try tilted surfaces. Angle a board covered in soil at 45 degrees and pour water down it. Compare to a flat surface. Slope increases runoff dramatically.

This experiment naturally leads to conversations about flooding, gardens, concrete in cities, and why trees and green spaces matter.