Illinois Grade 2 Science

Compare designs that slow water’s effect on a model slope

Compare original model-slope observations, explain a design’s limits, and plan a fair follow-up using a selected Illinois Grade 2 Earth science reference.

The Illinois science standards directory identifies NGSS as the science standards and links the standards publisher. Use the Illinois Learning Standards for Science document for the selected performance expectations and their examples and boundaries. This activity selects a Grade 2 expectation. It is one part of a science course, not a complete curriculum.

Which barrier helps the model slope hold its shape?

A teacher prepares three shallow trays with the same amount of sand and the same slope. One has no barrier, one has a low row of pebbles, and one has strips of firmly attached model vegetation. The same amount of water is poured from the same height along the top of each slope. Students compare the sand reaching the collection area. The record below is invented for discussing evidence; it does not claim that one design always works best outdoors.

Explain the evidence or model

The example shows the most sand in the collection area without a barrier and the least behind the model vegetation. That supports choosing the vegetation design for this particular model and water trial. The pebble row also slows the movement compared with the unprotected slope, so it is useful to compare more than a winner and a loser. Students should point to both the movement of sand and a change in the slope’s shape. The designs are intended to reduce water’s effects; they do not stop the water itself from existing or prove that no land can change.

What to check in the explanation

Keep the initial slope, sand, water amount, pour location, and observation time comparable. If the vegetation tray starts flatter or receives less water, the result cannot fairly isolate the design. Qualitative words such as more and less are appropriate here, but decide what counts as sand in the collection area before comparing. Model vegetation represents one design feature; it does not include roots growing through real soil, storms, different soil types, or the needs of living plants.

Plan the next activity

1. Compare each slope’s shape before the water is added.
2. Use the same pour and observation method for each design.
3. Explain the choice using the observed sand movement and a limitation.

Repeat with freshly rebuilt, comparable slopes and keep each trial’s record. If the same pattern appears, explain why repeated evidence is stronger than one successful pour. Change only one design feature in a later round, such as the position of the pebble row, and predict how that might redirect the water. Ask what constraints matter before an outdoor solution is chosen: available space, materials, maintenance, and the site’s water flow. This classroom comparison begins the expectation; it does not prescribe an erosion project for an actual property.