Materials Around Us — Objects and Properties (1 of 3) · Answer guide

Lesson 1 · Distinguish objects from their materials

Identify an object, its parts and the materials used to make those parts.

1. Which word names a material rather than an object?

   Answer: Wood. Wood can be used to make many different objects. Stool and comb name objects.

2. A bottle has a steel body and a plastic cap. Which record is most accurate?

   Answer: Body: steel; cap: plastic. A part-by-part record preserves both observed materials.

3. Two bowls have the same shape, one steel and one clay. What does this show?

   Answer: One type of object can use different materials. The object category is bowl, but its material can differ.

Discuss: Draw one safe intact object. Label two parts and the evidence for each material. Write “not sure” instead of guessing a hidden part.

Teaching note: An object and a material are not interchangeable names. A shiny appearance does not prove the entire item is metal. Open responses need discussion; they are not automatically marked.

Explain or demonstrate

Create a part-and-material record for one safe object, including one uncertainty if a part is hidden.

Evidence to include:

• Object named separately from material
• Two part labels linked to materials
• Observation, label or uncertainty stated

Review guide:

• 1 point: object and material terms distinguished
• 1 point: each part matched to its material
• 1 point: evidence or uncertainty reported

Example response: A lunch bag has a cloth panel and a plastic buckle. I can read the buckle label; I cannot identify the lining, so I record it as uncertain.

Lesson 2 · Classify using a clear rule

Group the same collection in more than one defensible way and connect properties to purpose.

1. A red wood cube and red plastic disc are grouped together. Which rule fits?

   Answer: Colour. Their shared feature is red colour; their material and shape differ.

2. What should be stated before judging a grouping?

   Answer: The grouping rule. A clear criterion lets another person check each member.

3. The same items are regrouped by shape instead of colour. Which statement is true?

   Answer: Group membership can change without the items changing. A new criterion can produce new groups for unchanged items.

Discuss: Group six safe objects by two different rules. Name each rule, explain one changed membership, and choose which grouping would help find an object quickly.

Teaching note: There need not be only one correct grouping. It becomes unfair when the rule changes for some items but not others. Open responses need discussion; they are not automatically marked.

Explain or demonstrate

Use two rules to sort the same six safe objects. Explain which sorting helps a particular task.

Evidence to include:

• Two explicit criteria
• Membership consistent with each criterion
• A reason tied to the task

Review guide:

• 1 point per consistent rule
• 1 point: purpose-based explanation

Example response: I group card shapes by colour to plan a display, then by material to choose pieces that resist splashes. The display rule cannot by itself identify waterproof pieces.

Lesson 3 · Compare appearance and softness

Describe surface observations and use hardness or softness as relative properties.

1. A shiny plastic folder shows that…

   Answer: Some non-metal objects can have shiny surfaces. Coatings and smooth plastic surfaces can shine.

2. Which observation best supports “sample A is softer than B” in a gentle-press test?

   Answer: A changes shape more easily under comparable pressure. The comparison concerns ease of deformation under the stated test.

3. A hard tile breaks when dropped. Which idea is corrected?

   Answer: Hardness does not mean unbreakable. Resistance to compression or scratching is different from resistance to breaking.

Discuss: Describe two safe samples using at least two properties. State which comparison supports “softer” and one conclusion the observations do not justify.

Teaching note: Hard does not mean impossible to break, and a shiny coating does not prove the underlying material is metal. Open responses need discussion; they are not automatically marked.

Explain or demonstrate

Write an evidence-based comparison of a sponge and an eraser using the same gentle-press method. A supplied observation record is acceptable.

Evidence to include:

• Comparable method
• Relative conclusion
• A limit on what the test shows

Review guide:

• 1 point: both samples described
• 1 point: comparative observation
• 1 point: no unsupported claim about identity or strength

Example response: Under similar gentle pressure the sponge changes shape more. In this test it is softer than the eraser. I have not tested which sample resists tearing.

Final check · Set 1

Try one set after the lessons. Use the other set after reviewing any errors.

1. A wooden toy and a wooden shelf illustrate which idea?

   One material can make different objects. Both use wood but perform different jobs.

2. A covered handle looks like metal but has no label. What should you record?

   Material uncertain; more evidence needed. Appearance alone is insufficient to identify a hidden or coated material.

3. A container must hold water without leaking. Which property is most relevant?

   Resistance to water passing through it. A container’s function sets the relevant property. Colour alone does not establish water resistance.

4. A group labelled “round objects” includes a square tile. What should be checked?

   Whether the tile meets the stated shape rule. Group membership should agree with the same rule for all items.

5. A dull metal object is observed. What is a sound conclusion?

   A metal surface need not always appear shiny. Surface changes or coatings can hide a metal’s lustre.

6. Which comparison is stated most clearly?

   This rubber sample compresses less easily than this sponge. This statement names both samples and the response being compared.

Final check · Set 2

Try one set after the lessons. Use the other set after reviewing any errors.

1. Which observation supports “this object uses several materials”?

   Its cloth strap is attached to a plastic clip. Different observed materials in named parts support the claim.

2. A plastic ruler and a metal ruler both measure length. What is a sound conclusion?

   Objects with a similar purpose can use different materials. Purpose can be shared even when materials differ.

3. Two learners sort by colour and by material. How can both defend their work?

   State each rule and check all members against it. Different useful criteria can produce different valid classifications.

4. Why might a shop group similar materials together?

   It can help locate and compare items. Organisation supports finding and studying items; it does not change their properties.

5. Which activity is suitable for this lesson?

   Compare a soft sponge and eraser with gentle finger pressure. Gentle comparison uses safe intact materials. Sharp or breaking tests are unnecessary.

6. A smooth object must also be…

   None of these: softness and mass need separate evidence. Smoothness describes texture and does not establish softness or mass.