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Science Launch G5 / Week 09 / Wednesday
3/6
Week 09 · Earth's Systems

Wednesday

Investigation: Rain on two hills
// Rock, water, air and life working together
⏱ about 15 min

Wednesday: Investigation: Rain on two hills

Rocket builds two small hills of damp soil on a big baking tray. They look exactly alike.

Raven covers one hill with a layer of leaves and grass clippings. The other stays bare.

"This is our model," she says. "Each hill is the geosphere. The leaves stand for plants."

Nova hovers over a paper cup with tiny holes poked in the bottom. "And this is the rain," she says. "Which hill will lose more soil?"

Rocket rubs his chin. "Let's predict before we pour," he says, sounding a lot like Raven.

What you need

  • A large tray or baking pan with sides
  • Damp soil or sand
  • Leaves, grass clippings or a paper towel to stand for plant cover
  • A paper cup with small holes in the bottom (a grown-up pokes the holes)
  • A cup of water
Safety first
A grown-up pokes the holes in the cup. Do not use sharp tools yourself.
Do this outdoors or over a sink to catch the muddy water.
Keep soil away from your mouth and eyes. Wash your hands when you finish.

Steps

  1. Build two equal hills of damp soil at one end of the tray.
  2. Cover one hill with leaves or a paper towel. Leave the other hill bare.
  3. Make your prediction below.
  4. Hold the holey cup over the bare hill. Pour half the water into it.
  5. Do the same over the covered hill with the rest of the water.
  6. Look at how much soil washed down from each hill.
MAKE A PREDICTION
  • Read the question.
  • Tap your answer.
Which hill do you predict will lose more soil?
HillHow much soil washed down?Was the water muddy or clear?
Bare hill
Covered hill

Plant cover softens the force of raindrops. That reduces soil erosion.

Your model shows two interactions: the hydrosphere moving the geosphere, and the biosphere protecting it.

Rain moving soil is an interaction between the hydrosphere and which other system? Type one word.
WHY THIS EXERCISEWater from the hydrosphere carried soil from the geosphere, which is erosion.

Two interactions in one model

The water you poured stood for rain, part of the hydrosphere.

The soil stood for the geosphere. The leaves stood for the biosphere.

Your results show how all three can interact.

MODEL THINKING
  • Read the question.
  • Tap your answer.
Why did both hills get the same amount of water?
What do plants do to raindrops?
StatementTrue or false?
Plant cover reduces soil erosion.?
The leaves stood for the geosphere.?
Muddy water is a clue that soil washed away.?
WHY THIS EXERCISELeaves stand for the biosphere, which protects the soil.

You modeled a real Earth process on a tray. Tomorrow we will see how slowly, and how surely, erosion works.

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