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Science Launch G4 / Week 11 / Wednesday
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Week 11 · Rock Layers and Weathering

Wednesday

Investigation: Rain on a slope
// Reading Earth's story and watching it change
⏱ about 15 min

Wednesday: Rain on a slope

After a big storm, Rocket notices a fan of mud at the bottom of the steep driveway. The gentle lawn looks fine.

"The rain hit both places," he says. "So why did only the driveway lose dirt?"

Raven crouches by the mud. "What do you notice about the slope of each place?"

Nova hovers at the top of the driveway, then glides down to the bottom. "My hint," she says. "Steep or gentle. Test one at a time."

What you need

  • A baking pan or plastic tray
  • Damp sand or soil, enough to fill half the pan
  • A paper cup
  • A pitcher of water
  • Two books and four books for tilting
  • A ruler and old towels
Safety first
A grown-up pokes five small holes in the bottom of the cup with a pencil.
Do this outside, in a bathtub or on towels.
Wash your hands after touching soil.

Steps

  1. Pack the damp sand into the top half of the pan. Leave the bottom half empty.
  2. Put two books under the sand end to make a gentle slope.
  3. Hold the cup over the top of the sand. Pour one cup of water into it to make rain.
  4. Measure how far the sand spread into the empty half.
  5. Repack the sand. Now use four books for a steep slope.
  6. Make the same amount of rain. Measure again.
MAKE A PREDICTION
  • Read the question.
  • Tap your answer.
Which slope will lose more sand to the rain?
SlopeHow far sand spread (cm)What the water did
Gentle (two books)
Steep (four books)
What one thing did you change in this test?
What did you keep the same? The amount of ____.

Steep or gentle?

Look at your table. Compare how far the sand spread on each slope.

On a steeper slope, water runs downhill faster.

Did your results match your prediction? Your results are your own evidence.

EROSION THINKING
  • Read the question.
  • Tap your answer.
Is the sand moving downhill weathering or erosion?
Why did you pour the same amount of water each time?
StatementTrue or false?
Small pieces of rock like sand are called sediment.?
Water can move sediment downhill.?
Changing two things at once makes a fair test.?
WHY THIS EXERCISEWater moves sediment, and a fair test changes only one thing.

You modeled erosion in a pan! Tomorrow we meet the forces that break rock apart.

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