Bendy or Rigid?

Overview

In this sixth lesson of Materials All Around Us, students investigate how everyday materials respond when they are bent or stretched. They predict, test, observe, and record whether materials bend, stretch, or stay rigid, building on earlier learning about identifying and describing material properties.

Learning intentions

• WALT observe and describe how materials respond to a force.
• WALT make a prediction before carrying out a fair test.
• WALT compare materials using the properties bendy, stretchy, and rigid.
• WALT record findings using drawings and simple sentences.

Success criteria

• I can make a sensible prediction about a material.
• I can test materials safely and carefully.
• I can describe what happened using bendy, stretchy, or rigid.
• I can draw and write about one test result.

Curriculum links

• Science — Physical Science: Materials and their properties.
• Science — exploring properties such as flexibility and elasticity.
• Science — comparing and grouping everyday materials according to shared physical properties.
• Te Mātaiaho learning capabilities: thinking, communicating, and participating and contributing through collaborative investigation.

Lesson structure (45 minutes)

1. 0–5 min · Hook and connect. Display a rubber band, wooden ruler, cardboard strip, paper strip, plastic spoon, and metal spoon. Open with the hook and learning intention slides and ask, “Which object would change shape if I gently pushed it? Which would spring back?” Students share observations from previous lessons and make quick predictions using thumbs up, sideways, or down.

2. 5–11 min · Teach the language. Demonstrate a gentle bend with the cardboard and ruler, then a gentle stretch with the rubber band. Explain that a material is bendy if it changes shape when pushed, stretchy if it gets longer when pulled and may spring back, and rigid if it is difficult to bend. Emphasise that we use gentle forces, do not snap or overstretch objects, and observe what happens. Students practise saying and acting out the three words.

3. 11–15 min · Model a fair test and recording. Use one object to model: predict, test in the same careful way, observe, and record. Show that a prediction can be different from the result and is still useful. Distribute the bendy or rigid investigation sheet and model drawing the object, circling a property, and completing the sentence: “The ___ is ___ because it ___.” Students repeat the sentence orally with a partner.

4. 15–29 min · Pair investigation. Organise 18 students into nine pairs and give each pair a tray containing four or five safe classroom materials. Suggested items include paper, cardboard, a fabric strip, a pipe cleaner, a rubber band, a plastic straw, a wooden pop stick, and a metal spoon. Students predict each material’s response, then test it by gently bending or stretching where appropriate. They record a drawing and property for at least four materials on the bendy or rigid investigation sheet. Circulate and ask, “What did you do?”, “What changed shape?”, and “Did it spring back?”

5. 29–36 min · Compare and group. Pause the investigation and return to the investigation instructions and property reminder slides. Pairs place their tested objects into three teacher-labelled areas: bendy, stretchy, or rigid. Students compare results with another pair and discuss any object that could fit more than one group. Clarify that some materials may bend a little but are not stretchy, while others may be both bendy and stretchy.

6. 36–42 min · Share evidence. Invite pairs to present one prediction and result using the frame, “We predicted ___ would be ___. We observed ___, so we think it is ___.” Record a class table on the board. Ask whether all pairs got the same result and why careful, gentle testing helps make comparisons fair. Students add one simple sentence or labelled drawing to their worksheet if needed.

7. 42–45 min · Exit check. Show a new classroom object, such as a cloth, pencil, or plastic lid, using the closing question slide. Students tell a partner whether it is bendy, stretchy, or rigid and give a reason. Collect worksheets as evidence of individual understanding.

Resources

• the Bendy or Rigid? lesson slide deck
• the bendy or rigid investigation sheet
• Nine trays or baskets for pairs
• Safe everyday materials: paper, cardboard, fabric, pipe cleaner, rubber band, plastic straw, wooden stick, and metal spoon
• Three labelled sorting areas or hoops: bendy, stretchy, rigid
• Pencils, crayons, and clipboards or firm writing boards
• Board or large paper for the class results table
• Optional camera or tablet for photographing groupings

Assessment

• Listen to predictions and questioning during the hook; note whether students use property words appropriately.
• Observe pairs testing gently and recording a result supported by an observation rather than a guess.
• Check each worksheet for a prediction, drawing, correct or reasonable property description, and a simple evidence sentence.

Differentiation

• Provide picture cues and the sentence frame “The ___ is ___ because it ___.” Allow students to explain orally while an adult records their words.
• Pre-select three contrasting materials for students needing reduced choice, and pair students thoughtfully with clear roles: tester, recorder, then swap.
• Support EAL learners by modelling actions for bend, stretch, and rigid; use gestures, real objects, and repeated oral rehearsal before writing.
• Extend confident students by asking them to explain why one material might be bendy but not stretchy, or to identify a material that could belong in two groups.
• Remind students not to pull rubber bands towards faces, twist materials near others, or use force that could break an object.