Choose a material for a spill mat

Which material best keeps a small water spill off the desk?

Submit: A material-test record and evidence-backed recommendation.

Related lesson: States of Matter

This is a teacher-led extension beyond the short lesson. The task supplies a performance opportunity; completion alone does not certify mastery, full NGSS coverage or state alignment.

Build the idea

Materials have observable properties such as absorbency, flexibility and strength. A useful choice depends on the job. A flexible material may still let water through; a waterproof sheet may keep water off a surface without absorbing it. Define the job before comparing materials.

Evidence and model inputs

Illustrative observations: paper towel absorbs water but tears when lifted wet; cotton cloth absorbs water and remains intact; plastic sheet does not absorb water, but water can run off its edge. The choice depends on whether the goal includes holding the spill in place. These descriptions must be checked against the actual supplied samples.

Keep actual observations, published findings and invented model cases labeled separately. If a source or required equipment is unavailable, pause that part with a teacher; do not invent results.

Materials and preparation

Equal-size paper towel, cloth and plastic samples; trays; a small controlled water supply; ruler; towels. Adult manages water and slippery surfaces.

Grade-level scope

Keep quantitative assessment to length; compare other properties through observations rather than mass, volume or temperature calculations.

Do the work

1. Define the mat’s job: hold a small spill, protect the desk and survive lifting.
2. Use equal-size pieces, the same adult-dispensed amount of water and the same waiting time. Place each in a tray.
3. Record whether water is absorbed, passes through or runs off, and whether the wet material stays intact.
4. Repeat each comparison. Measure sample length if needed; use words and drawings for the other properties.
5. Choose a material using at least two observations. Explain a tradeoff and propose a second test.

Learner worksheet

Write on paper or type here and print. Entries stay in this page’s memory and are lost when you leave or reload; they are not saved or submitted.

Check your reasoning

1. Is “best material” meaningful without a job?
2. Why use matching sample sizes?
3. Does not absorbing water mean a material cannot protect a desk?
4. Why might cloth beat paper towel for a reusable mat?

Teacher review guide

Review the actual deliverable and discuss the reasoning. For each criterion, use 0 when evidence is absent or fundamentally incorrect, 1 when partly supported with a material error or omission, and 2 when accurate, supported and complete for the stated task. Maximum 8 points is a task score, not a proficiency certification. Give feedback and allow revision.

1. States criteria tied to the intended purpose.
2. Conducts fair, repeated material tests.
3. Compares at least two relevant properties using observations.
4. Justifies a choice and acknowledges a tradeoff.

Sources and standard reference

• Official NGSS 2-PS1-2 performance expectation — inspect the practice, core idea, crosscutting concept and assessment boundary.

Instructional text and hypothetical cases are original. Linked source readings supply published evidence where specified. Teachers should judge fit with their course and state requirements.