Wind can never change the shape of land.

Which action is an example of erosion?

• Water freezing in a rock crack
• Wind carrying soil across a field
• A root pushing a crack wider

Which of these is a solution people use to slow erosion?

• Planting grass so its roots hold soil
• Removing grass from the slope
• Pouring more water down the slope

A windbreak is a row of trees or a fence. How can it reduce wind erosion?

• It slows wind near loose soil
• It adds water to the soil
• It blows soil away from the field

Matching model hills receive equal amounts of water for the same length of time. Only their protection differs. Adults collect, dry and weigh all soil washed out. The chart shows the same results in grams (g) for all three tests. Which design protects best in these tests?

• No cover, because the largest mass washed out
• Plants, because less washed out than with no cover
• Wall, because the least soil washed out

A class compares bare and planted model hills. Which plan makes the rain test fair?

• Use different slopes and pour equal water
• Use matching hills and equal water for equal time
• Use matching hills but pour water only on the bare one

Equal rain carries soil away from matching model slopes. At marked spots, the surface drops 9 cm without plants and 3 cm with plants. How many fewer centimeters does it drop with plants?

Ravi says a wall and grass protect soil in exactly the same way, so comparing them is unnecessary. Which reply explains why testing helps?

• They work in the same way, so comparing them adds nothing
• Grass cannot protect soil, so test only walls
• They work differently, so compare their test results