Arkansas Grade 2 Science

Choose a material using evidence from a test

Test materials for a model roof, compare bending and water observations, and explain a Grade 2 design choice using Arkansas science references.

Curriculum source: Arkansas’s Grade 2 science document, linked by the state science standards office. The document retains its 2015 science framework and notes its fall 2024 realignment to other Arkansas academic standards.

Which sheet would work for a small model roof?

A class compares equal-sized pieces of paper towel, thin cardboard, and flexible plastic for a toy building’s roof. Each sheet rests across the same gap. The class places the same small block at the center and adds the same small amount of water in a separate water test. The goal is a roof that spans the gap and keeps the space underneath dry. These are sample classroom observations, not a report from an actual experiment.

Explain the result

Suppose the paper towel bends and lets water through, the cardboard holds the block but becomes damp, and the plastic keeps water out but sags under the block. No sample meets both goals by itself. Plastic is useful for blocking water, while cardboard provides better support in this test. A design using a plastic outer layer over a supported cardboard sheet is a proposal worth testing, not a proven winner. The choice comes from observed properties and the intended job.

What to check in the explanation

“Plastic is best” ignores the sagging result. “Cardboard is strong” also needs context: this piece supported this small block across this gap. Ask the student to connect each observation to one roof requirement. Check that the pieces have comparable sizes and that the gap and block stay the same. A classroom material test cannot establish that a design is suitable for a real house.

Plan the next activity

1. Name the two requirements before testing: span the gap and keep water from passing through.
2. Record each sample’s bending and water results in separate columns.
3. Use the table to propose a roof, then test the proposed combination with the same setup.

If the combination sags or leaks at the edges, sketch where it failed and revise one feature, such as the support spacing. Compare the revised roof with the first version. Have the child finish the sentence, “We changed ___ because our test showed ___.” This connects a design decision to evidence instead of to a favorite color or material.