Outdoor Erosion Experiment for Kids
Build small hills of soil and pour water over them to observe erosion — test how plants, mulch, and rocks affect water flow and soil loss.
What You'll Need
- 1Garden soil for building mounds
- 2Watering can
- 3Small plants or grass transplants
- 4Mulch or small pebbles
- 5Angled board or slope area
- 6Trays to catch runoff
What You'll Need
Garden soil for building three mounds
A large watering can
Small plants, grass plugs, or transplanted patches of lawn
Mulch or small pebbles
An angled board or a natural slope
Trays or shallow containers to catch runoff
How to Play
Build three identical small mounds of soil, each about 8 inches tall. Place them on a slight slope or on angled boards so water will flow downward.
Leave Mound 1 completely bare. Press small plants or grass patches into Mound 2 (roots are key — they hold soil). Cover Mound 3 with a layer of mulch or small pebbles.
Place a tray at the bottom of each slope to catch runoff and any soil that washes away.
Before pouring, ask your child: "Which mound do you think will lose the most soil? Which will hold together best?" Write down predictions.
Pour identical amounts of water from the watering can over each mound from the same height. Go slowly so you can observe the water flow in real time.
Check the trays. The bare mound's tray will be full of muddy, soil-laden water. The planted mound's tray will be much cleaner. The mulched one falls somewhere in between. "Why? What's different about the planted mound?" Roots hold the soil in place.
Tips
The visual contrast between bare soil erosion and plant-protected soil is dramatic. Your child will see immediately why forests, meadows, and ground cover matter.
Connect to real-world erosion: riverbanks, hillsides after wildfire, construction sites. Why do builders put up silt fences?
For a deeper experiment, vary the water intensity. A gentle pour versus a hard pour shows how heavy rain causes more damage than drizzle.
This is genuine environmental science. Erosion control is a field of engineering — and your child just ran a real experiment.
Age Adaptation Tips
School-age kids can take more ownership. Let them lead the activity, experiment with variations, and explain what they learned.
Frequently Asked Questions
How long does this activity take?
This activity takes about 30 min, with 15 min of preparation time beforehand.
What materials do I need?
You'll need: garden soil for building mounds, watering can, small plants or grass transplants, mulch or small pebbles, angled board or slope area, and 1 more item.
What age is this activity for?
This activity is designed for 5-8 years. You can adapt it for younger or older children by adjusting the complexity.
Does this need to be done outdoors?
This activity is best done outdoors where kids have space to move and explore.
How difficult is this activity?
This activity has a moderate difficulty level. It may require some preparation or guidance, but is manageable for most families.
Ratings & Reviews
Sign in to leave a rating or review.
Add to Your Weekly Plan
Schedule this activity into your family's week. It takes about 30 min.
Free account required to save plans
Explore More
Love this activity?
Create a free account and add it to your weekly planner. Discover hundreds more activities matched to your child's age.