Strong or Weak?

Overview

In this seventh lesson of Materials All Around Us, students investigate strength by testing which everyday materials can support classroom objects. They build on earlier learning about material properties, make simple predictions, observe results, and discuss how to make a test fair.

Learning intentions

• We are learning to describe strength as a material property.
• We are learning to test which materials can support an object.
• We are learning to make a fair comparison.
• We are learning to record and discuss our results.

Success criteria

• I can make a prediction about which material will be strong or less strong.
• I can help carry out a fair test safely.
• I can describe what happened using words such as strong, less strong, held, and collapsed.
• I can record and share evidence from my group’s test.

Curriculum links

• Science — Physical Science: comparing and grouping everyday materials according to shared physical properties.
• Science — Materials and their properties: exploring how materials respond when forces are applied.
• Science — Science capabilities: participating in investigations, observing carefully, recording evidence, and communicating findings.
• Te Mātaiaho learning area expectations: asking questions, testing ideas, and using evidence to explain observations.

Lesson structure (45 minutes)

1. 0–5 min · Hook and recall. Teacher opens the hook and recall slides and shows a paper bridge holding no objects, then asks, “What might happen if we put a classroom object on it?” Students turn and talk, recall properties studied previously, and share ideas about what makes a material strong.

2. 5–12 min · Introduce strength and fair testing. Teacher uses the strength and fair-testing slides to explain that a strong material can support a load without bending or collapsing easily; model comparing two strips of material placed across the same two supports. Students help identify what must stay the same, including the supports, the object added, the material size, and the way the test is carried out.

3. 12–16 min · Predict and demonstrate. Teacher demonstrates the test with one material and models a safe method: place the strip across two identical supports, add one classroom object at a time, stop if it bends or falls, and record the result. Students examine the available materials, make a group prediction, and practise saying, “I think ___ will be stronger because ___.”

4. 16–29 min · Group investigation. Teacher places students in six groups of three, assigns roles of tester, object counter, and recorder, and distributes the strength investigation worksheet. Students test several prepared material strips, such as paper, cardboard, fabric, and thin plastic, using the same supports and similar classroom objects; they add objects one at a time and record how many each material supports before bending or collapsing.

5. 29–36 min · Compare results. Teacher pauses the investigation and displays the results comparison slides. Groups compare their results, then discuss: “Which material supported the most?” “Did every group get the same result?” and “What might have made the test unfair?” Students share evidence, notice patterns, and suggest improvements such as using equal-sized strips or the same objects.

6. 36–42 min · Complete and explain. Teacher guides students to finish the strength investigation worksheet, including a picture or simple table showing strong and less-strong materials. Students draw or label their results and complete the sentence, “The strongest material in our test was ___ because it supported ___ objects.”

7. 42–45 min · Plenary and exit check. Teacher returns to the plenary question slide and asks students to show a thumbs-up, sideways, or down for the statement, “A material is strong if it can support a load without collapsing.” Students share one finding and one feature of a fair test before handing in their worksheets.

Resources

• the Materials All Around Us slide deck
• the strength investigation worksheet
• Prepared strips of paper, cardboard, fabric, and thin plastic
• Two identical supports for each group, such as blocks or books
• Small classroom objects for testing, such as counters, cubes, or toy bricks
• Trays for organising group materials
• Pencils and crayons
• Teacher clipboard or class results chart

Assessment

• Listen for students using evidence when making predictions and explaining which material supported the greatest load.
• Observe whether groups keep key features of the test the same and record results accurately; prompt with, “What are we changing?” and “What are we keeping the same?”
• Use the completed worksheet and final response to check whether students can identify a strong or less-strong material and explain their choice.

Differentiation

• Support students with picture labels, pre-measured material strips, assigned group roles, and the sentence starters: “I predict ___,” “We observed ,” and “ was stronger because ___.”
• Reduce the number of materials or objects for students who need a shorter investigation, and provide adult support for counting and recording.
• Provide a word bank with strong, less strong, bend, collapse, support, same, and fair; allow students to draw findings before explaining them orally.
• Extend confident students by asking them to suggest a more reliable test, explain why groups may have different results, or redesign a material strip to support more objects.
• Use gestures, real objects, repeated modelling, and partner talk to support English language learners and students with communication or sensory needs. Ensure objects are safe to handle and stop testing if materials or objects fall.