Year 5 Science: Hardness and transparency
Part of the Year 5 Science properties and uses of materials chapter. Chapter overview · whole chapter on one page
Hardness and transparency
A property is a feature of a material that we can describe or measure, such as how hard it is or whether light can pass through it.
Hardness can be tested by scratching: a harder material makes fewer scratches on a softer test board. Transparent materials let you see clearly through them. Translucent materials let light through, but you cannot see clearly through them. Opaque materials do not let light through at all.
| Material | See-through? | Conducts electricity? | Conducts heat? | Pulled by a magnet? |
|---|---|---|---|---|
| iron nail | no | yes | yes | yes |
| aluminium foil | no | yes | yes | no |
| copper wire | no | yes | yes | no |
| clear glass | yes | no | no | no |
| clear plastic bottle | yes | no | no | no |
| wooden block | no | no | no | no |
| rubber band | no | no | no | no |
| Material | Number of scratches on the test board |
|---|---|
| clear glass | 0 |
| wooden block | 3 |
| iron nail | 2 |
Key ideas
- A property is a feature of a material that can be described or measured.
- A transparent material lets you see clearly through it.
- An opaque material does not let light through.
- A harder material makes fewer scratches than a softer one, in a fair scratch test.
Method. Read the see-through column.
- Read the row for each material. The clear glass row says yes, and the wooden block row says no.yes and no
- Choose the see-through one. So the see-through material is clear glass.clear glass
- Write the answer. clear glass
Check. You can see through clear glass. ✓
Method. Read the scratch table.
- Read the counts. The wooden block has 3 scratches, the iron nail 2, and the clear glass 0.3, 2, 0
- Choose the largest. The most scratches were made by the wooden block.wooden block
- Write the answer. wooden block
Check. The wooden block was the softest of the three in this test. ✓
Method. Read the scratch table.
- Find the zero. The clear glass row has 0 scratches.0
- Name the material. So the material with no scratches is clear glass.clear glass
- Write the answer. clear glass
Check. The glass did not mark the board in this test. ✓
Watch out
Watch out: a material that is hard to scratch is not always the same as one that is see-through. A property is tested separately, so look at each column on its own.
Try it (with your teacher). Take three small pieces of different materials (for example a plastic lid, a piece of card and a coin). With your teacher, gently scratch a soft board with each material, using the same pressure every time. Count the scratches. Then hold each material up to a window and say whether you can see through it.
Exam tip
Grown-up tip. Ask: “Which material is see-through? Which made the fewest scratches?” Let your child keep the test the same each time.
Exercise 5A Hardness and transparency
Method. Read the see-through column.
- Read the rows. The clear plastic bottle row says yes, and the copper wire row says no.yes and no
- Choose the see-through one. So the see-through material is the clear plastic bottle.clear plastic bottle
- Write the answer. clear plastic bottle
Check. Clear plastic lets you see through it. ✓
Method. Read the see-through column.
- Read the rows. The wooden block row says no, so you cannot see through it.no
- Choose the opaque one. So the opaque material is the wooden block.wooden block
- Write the answer. wooden block
Check. Clear glass is transparent, so it is not opaque. ✓
Method. Count the rows that say yes in the see-through column.
- Read the column. The rows that say yes are clear glass and clear plastic bottle.two yes rows
- Count them. So there are two see-through materials.2
- Write the answer. 2
Check. The other five materials are not see-through. ✓
Method. Read the scratch table.
- Read the table. The iron nail row shows 2 scratches.2
- Write the number. So the iron nail made 2 scratches.2
- Write the answer. 2
Check. The wooden block made 3 scratches. ✓
Method. Read the scratch table.
- Read the counts. The counts are 0 for clear glass, 3 for the wooden block and 2 for the iron nail.0, 3, 2
- Choose the answer. Clear glass made none, so the fewest scratches but some is the iron nail.iron nail
- Write the answer. iron nail
Check. Clear glass made no scratches at all. ✓
Method. Add the three counts.
- Add the counts. The counts are 0, 3 and 2.0 + 3 + 2
- Find the total. The total is 5 scratches.5
- Write the answer. 5
Check. Check: 3 + 2 = 5. ✓
Method. Read the see-through column.
- Read the column. The rows that say no are the iron nail, aluminium foil, copper wire, wooden block and rubber band.five rows
- Name two. Two of the materials that are not see-through are the wooden block and the rubber band.wooden block and rubber band
- Write the answer. wooden block and rubber band
Check. Any two of the five opaque materials are a correct answer. ✓
Method. Read the key ideas in section 5.1.
- Read the key idea. A transparent material lets you see clearly through it.see clearly through
- Fill the gap. So the missing word is transparent.transparent
- Write the answer. transparent
Check. Opaque materials let no light through. ✓
Method. Read the key ideas in section 5.1.
- Read the key idea. An opaque material does not let light through.does not let light through
- Fill the gap. So the missing word is opaque.opaque
- Write the answer. opaque
Check. Wood and metal are opaque. ✓
Method. Think about what makes a scratch test fair.
- Think about the test. Only the material should change between tests.only the material
- Write one thing. The pressure, the board and the number of strokes must stay the same.stay the same
- Write the answer. Accept any one of: the same pressure, the same test board, the same number of strokes.
Check. A fair test changes only one thing. ✓
Method. Think about the scratch test.
- Think about the material. A harder material resists being marked.resists being marked
- Write the reason. So it makes fewer scratches on the test board.fewer scratches
- Write the answer. Accept any sentence that says a harder material is less easily marked, so it makes fewer scratches on the board.
Check. Hardness is judged by the scratches in a fair test. ✓