Changing shape
By the end of this chapter you will be able to
- Name the four ways to change shape: squash, bend, twist and stretch
- Say which materials change shape easily, and which change shape only a little
- Say whether an object springs back or stays changed
- Test one thing at a time, using the same push each time
- Record fair test results in a table and read them
You should already know
- Hard, soft, bendy and stiff materials (Year 1 Science, Chapter 8)
- Uses of everyday materials (Year 2 Science, Chapter 9)
Where this leads
- Rocks, fossils and soils (Year 3 Science, Chapter 7)
- Forces (Year 3 Science, Chapter 9)
National Curriculum for England, Key Stage 1 science, Year 2. Content: Find out how the shapes of solid objects made from some materials can be changed by squashing, bending, twisting and stretching.
Exercise P Do you remember?
Method. Think about what a sponge does when you press it.
- Look at the sponge. A sponge squashes when you press it.squashes
- Write the answer. Things that squash are soft.soft
- Write the answer. soft
Check. A sponge is soft. ✓
Watch out. Stone is hard, and it does not squash.
Method. Count the sponges once each. Touch each one as you count it.
- Count them one at a time. Say each number as you touch one.1 2 3
- Read the last number. The last number is how many there are.3
- Write the answer. 3
Check. Count them again from the other end. You get 3 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Think about metal and pressing.
- Look at the metal bar. Metal is hard and stiff, so it does not squash by hand.hard
- Write the answer. So a metal bar does not squash.no
- Write the answer. no
Check. Metal does not squash when we press it by hand. ✓
Watch out. A thick metal bar is too stiff to squash by hand.
Method. Think about which material lets light through.
- Check glass. Glass is see-through, so light gets through.glass
- Check wood. Wood is not see-through, so it blocks the light.wood
- Write the answer. glass
Check. Glass is see-through. ✓
Watch out. Wood does not let light through.
Method. Think about which one is more bendy.
- Check straw. A plastic straw is light and bends easily.straw
- Check stick. A wooden stick is stiff and does not bend much.stick
- Write the answer. straw
Check. The plastic straw bends more easily. ✓
Watch out. Wood is stiff.
Four ways to change shape
The shape of an object is what it looks like.
A push or a pull can change the shape of some objects. There are four ways to change shape.
Squash means pressing something so it gets flatter.
Bend means curving something so it is not straight.
Twist means turning one end while the other end stays still.
Stretch means pulling something so it gets longer.
Some materials change shape easily. A sponge, play dough and a straw do.
A thick block of wood or metal changes shape only a little. A stone does not change shape at all.
Key ideas
- Squash, bend, twist and stretch are four ways to change shape.
- Play dough, sponges and straws change shape easily.
- Wood and metal change shape only a little.
- A stone does not change shape when you push it by hand.
Method. Think about what each word means.
- Check squash. Squash means pressing something so it gets flatter.squash
- Check twist. Twist means turning one end while the other end stays still.twist
- Write the answer. squash
Check. Pressing a sponge flat is squashing. ✓
Watch out. Twisting turns the ends, it does not press flat.
Method. Think about what is happening to the dough.
- Check stretch. Pulling something to make it longer is stretching.stretch
- Check bend. Bending curves something, so it is not longer.bend
- Write the answer. stretch
Check. Pulling the dough long is stretching. ✓
Watch out. Stretching makes things longer.
Method. Think about what a stone is like.
- Look at the stone. A stone is hard, so it does not squash or bend by hand.hard
- Write the answer. So a stone does not change shape when pushed by hand.no
- Write the answer. no
Check. A stone does not change shape by hand. ✓
Watch out. Some materials change shape easily; others hardly change at all.
Watch out
Watch out: some materials change shape only a little. Wood and metal are hard to squash, bend or twist by hand.
Try it at home (with a grown-up). Look around the kitchen together. Find one thing that squashes, one that bends and one that does not change shape. Say how you know. Do not press anything sharp.
Exam tip
Grown-up tip. Ask: “Which thing could you squash?” Let your child point and name it. Praise every answer, even if it is not quite right.
Exercise 10A Four ways to change shape
Method. Look at each word and ask if it changes shape.
- Check squash. Squash is one of the four ways.squash
- Check bend. Bend is one of the four ways.bend
- Check drop. Dropping is not one of the four ways to change shape.drop
- Check stretch. Stretch is one of the four ways.stretch
- Write the answer. drop
Check. Drop is not one of the four ways. ✓
Watch out. The four ways are squash, bend, twist and stretch.
Method. Look at what has happened to the straw.
- Look at the straw. The straw is curved at a kink.curved
- Write the word. Curving something is bending it.bend
- Write the answer. bend
Check. A curved straw has been bent. ✓
Watch out. Squash means pressing flat.
Method. Look at the stripes on the towel.
- Look at the towel. The stripes slant, so the ends have been turned.slanted
- Write the word. Turning one end while the other stays still is twisting.twist
- Write the answer. twist
Check. A towel with slanted stripes has been twisted. ✓
Watch out. Bending is curving, not turning.
Method. Look at the rubber band.
- Look at the band. It is longer than it was, after being pulled.longer
- Write the word. Pulling something to make it longer is stretching.stretch
- Write the answer. stretch
Check. A band pulled long has been stretched. ✓
Watch out. Squashing makes things flatter.
Method. Look at the first picture.
- Look at the sponge. It is a sponge at rest, not pressed.at rest
- Write the answer. no
Check. The first sponge has not changed shape. ✓
Watch out. Look for a squashed or bent shape.
Method. Look at the second picture.
- Look at the sponge. It has been pressed flat.pressed flat
- Write the answer. yes
Check. The second sponge has been squashed. ✓
Watch out. A flat sponge has been squashed.
Method. Look at the third picture.
- Look at the straw. It is straight, not bent.straight
- Write the answer. no
Check. The straw has not been bent. ✓
Watch out. A straight straw has not changed shape.
Method. Count the balls of play dough once each. Touch each one as you count it.
- Count them one at a time. Say each number as you touch one.1 2 3 4 5
- Read the last number. The last number is how many there are.5
- Write the answer. 5
Check. Count them again from the other end. You get 5 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Think about which one changes shape easily.
- Check wood. Wood is stiff, so it changes shape only a little.wood
- Check play dough. Play dough changes shape easily when you press or pull it.play dough
- Write the answer. play dough
Check. Play dough changes shape more easily. ✓
Watch out. Wood is hard to change by hand.
Method. Think about wood and pressing.
- Read Sam’s idea. Sam says a wooden block is easy to squash.easy
- Check the idea. Wood changes shape only a little, so Sam is not right.only a little
- Write the answer. no
Check. Sam is not right. Wood is hard to squash. ✓
Watch out. Wood changes shape only a little by hand.
Method. Make a prediction from what you know about stones.
- Think about a stone. A stone is hard and does not squash.hard
- Make the prediction. So a stone will not change shape when squashed.no
- Write the answer. no
Check. A prediction is a sensible guess that we can check. ✓
Watch out. You can check with a grown-up, using a soft object and a hard object.
Method. Think about what play dough does after you squash it.
- Think about play dough. Play dough keeps the shape you press it into.keeps shape
- Give the reason. So it stays squashed and shows the new shape.stays squashed
- Write the answer. it stays squashed
Check. Also accept: it keeps its shape, it stays flat. ✓
Watch out. Give a reason about what the dough does after you let go.
Method. Think about metal bars and hands.
- Read Ali’s idea. Ali says a metal bar bends a lot.bends a lot
- Check the idea. A metal bar changes shape only a little, so Ali is not right.only a little
- Write the answer. no
Check. Ali is not right. Metal changes shape only a little. ✓
Watch out. Thin metal wire can bend, but a bar does not bend much.
Squashing: springs back or stays squashed
When we squash something, we press it so it gets flatter or smaller.
Some materials spring back. When we let go, they go back to their old shape. A sponge springs back.
Other materials stay squashed. Play dough keeps the flat shape we press it into.
To test squashing fairly, use the same push each time.
Key ideas
- Squashing presses something flatter.
- A sponge springs back when we let go.
- Play dough stays squashed.
- Use the same push for each thing you test.
Method. Think about what a sponge does after it is squashed.
- Check springs. A sponge goes back to its old shape, so it springs.springs
- Check stays. A sponge does not stay squashed when we let go.stays
- Write the answer. springs
Check. A sponge springs back. ✓
Watch out. A sponge goes back to its shape.
Method. Think about which one keeps its squashed shape.
- Check sponge. A sponge springs back when we let go.sponge
- Check play dough. Play dough stays squashed when we let go.play dough
- Write the answer. play dough
Check. Play dough stays squashed. ✓
Watch out. The sponge goes back to its old shape.
Method. Think about play dough after squashing.
- Think about the dough. Play dough stays in the shape it is pressed into.stays
- Write the answer. So play dough does not spring back.no
- Write the answer. no
Check. Play dough does not spring back. ✓
Watch out. Only some materials spring back, such as a sponge.
Watch out
Watch out: some things squash and stay squashed, and some squash and spring back. Test each one to find out.
Try it at home (with a grown-up). Hold a damp sponge and squash it, then let go. Does it spring back? Then press a small ball of play dough flat. Does it stay flat? Do not put play dough in your mouth.
Exam tip
Grown-up tip. Ask: “What do you think will happen when we let go?” Let your child predict first, then test. Keep the sponge and dough on a tray.
Exercise 10B Squashing: springs back or stays squashed
Method. Think about what a sponge does after squashing.
- Look at the sponge. A sponge goes back to its old shape.springs back
- Write the answer. So a sponge does spring back.yes
- Write the answer. yes
Check. A sponge springs back. ✓
Watch out. Play dough does not spring back.
Method. Think about play dough after squashing.
- Look at the dough. Play dough stays in the shape you press it into.stays
- Write the answer. So play dough does not spring back.no
- Write the answer. no
Check. Play dough stays squashed. ✓
Watch out. Sponges spring back, play dough does not.
Method. Think about the sponge.
- Look at the sponge. A sponge goes back to its shape.springs
- Write the answer. springs
Check. A sponge springs back. ✓
Watch out. A sponge does not stay squashed.
Method. Think about the play dough.
- Look at the dough. Play dough keeps the new shape.stays
- Write the answer. stays
Check. Play dough stays squashed. ✓
Watch out. Play dough does not spring back.
Method. Read the sentence and think about the sponge.
- Read the gap. The gap is what a sponge does when it is let go.let go
- Fill the gap. A sponge springs back to its shape.springs
- Write the answer. springs
Check. A sponge springs back. ✓
Watch out. Stays is for things that do not spring back.
Method. Count the sponges once each. Touch each one as you count it.
- Count them one at a time. Say each number as you touch one.1 2 3 4
- Read the last number. The last number is how many there are.4
- Write the answer. 4
Check. Count them again from the other end. You get 4 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Find each count, then add them all together.
- Write down each count. Each count is one row.sponges 4, play dough 3
- Add the counts together. Add them all, so none is missed.4 + 3 = 7
- Write the answer. 7
Check. Add them again, starting from the last count, and you get 7. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Make a prediction about the push.
- Think about the push. A bigger push presses the sponge flatter.bigger push
- Make the prediction. So a big push makes the sponge flatter.yes
- Write the answer. yes
Check. A prediction is a sensible guess that we can check. ✓
Watch out. Test it with the same sponge, using a small push and then a big push.
Method. Think about which one squashes when you press it.
- Check sponge. A sponge squashes when we press it.sponge
- Check wooden block. A wooden block is hard and does not squash.wooden block
- Write the answer. sponge
Check. A sponge squashes. ✓
Watch out. Wood is hard and stiff.
Method. Think about what each one does when Tom lets go.
- Check sponge. The sponge springs back when Tom lets go.sponge
- Check play dough. The play dough stays squashed, so it stays changed.play dough
- Write the answer. play dough
Check. Play dough stays changed. ✓
Watch out. The sponge goes back to its shape.
Method. Think about what a sponge does.
- Read Ben’s idea. Ben says a sponge stays squashed.stays
- Check the idea. A sponge springs back, so Ben is not right.springs back
- Write the answer. no
Check. Ben is not right. A sponge springs back. ✓
Watch out. Look at what a sponge does after you let go.
Method. Think about a fair test. Only one thing should change.
- Check push. The push must stay the same, so the test is fair.push
- Check wetness. The wetness is the one thing Ella changes on purpose.wetness
- Write the answer. push
Check. Keep the push the same, and change only the wetness. ✓
Watch out. Change one thing at a time.
Bending: a kink stays, a pipe cleaner stays bent
When we bend something, we curve it so it is no longer straight.
A pipe cleaner bends easily. It stays in the shape you bend it to.
A plastic straw can kink. The kink stays in the straw.
A thin card strip bends easily. A thin strip bends more than a thick strip.
Wood and metal change shape only a little when we bend them by hand.
Key ideas
- Bending curves something so it is not straight.
- A pipe cleaner stays in the shape you bend it.
- A straw can kink, and the kink stays.
- Thick wood and metal change shape only a little.
Method. Think about a pipe cleaner after bending.
- Think about the pipe cleaner. A pipe cleaner keeps the bend we give it.keeps bend
- Write the answer. So a pipe cleaner stays in its new shape.yes
- Write the answer. yes
Check. A pipe cleaner stays bent. ✓
Watch out. A wooden stick is stiff and does not bend much.
Method. Think about which one is thin and bendy.
- Check card strip. A thin card strip bends easily.card strip
- Check wooden stick. A wooden stick is stiff and does not bend much.wooden stick
- Write the answer. card strip
Check. The card strip bends more easily. ✓
Watch out. Wood is stiff.
Method. Look at the straw.
- Look at the straw. The straw is curved at a kink.kink
- Write the answer. A curved straw is bent, so the answer is yes.yes
- Write the answer. yes
Check. A kinked straw is bent. ✓
Watch out. A straight straw is not bent.
Watch out
Watch out: a bent shape that springs back is not the same as a bent shape that stays. Test each one yourself.
Try it at home (with a grown-up). Bend a plastic straw gently in the middle. Does the kink stay? Then bend a pipe cleaner into a curve. A grown-up checks each bend. Do not bend anything until it snaps.
Exam tip
Grown-up tip. Ask: “Which one stays bent, the straw or the pipe cleaner?” Let your child predict first. Keep every bend gentle.
Exercise 10C Bending: a kink stays, a pipe cleaner stays bent
Method. Look at the straw.
- Look at the straw. The straw has a curve at a kink.curve
- Write the word. A straw with a curve is bent.bent
- Write the answer. bent
Check. A curved straw is bent. ✓
Watch out. A straight straw is not bent.
Method. Think about wood and bending.
- Look at the stick. Wood is stiff and changes shape only a little.stiff
- Write the answer. So a wooden stick is not easy to bend.no
- Write the answer. no
Check. Wood is stiff. ✓
Watch out. Wood changes shape only a little by hand.
Method. Look at the first picture.
- Look at the pipe cleaner. It is curved into a U shape.U shape
- Write the answer. bent
Check. The pipe cleaner is bent. ✓
Watch out. A U shape is a bend.
Method. Look at the second picture.
- Look at the stick. It is a straight stick.straight
- Write the answer. straight
Check. The stick is straight. ✓
Watch out. A stick can be straight and stiff.
Method. Look at the third picture.
- Look at the straw. It is a straight straw.straight
- Write the answer. straight
Check. The straw is straight. ✓
Watch out. A straight straw has no kink.
Method. Read the sentence and think about a pipe cleaner.
- Read the gap. The gap is what a bent pipe cleaner does.bent
- Fill the gap. A pipe cleaner stays in the shape you bend it.stays
- Write the answer. stays
Check. A pipe cleaner stays bent. ✓
Watch out. Springs back is for things that go back to their shape.
Method. Count the straight straws once each. Touch each one as you count it.
- Count them one at a time. Say each number as you touch one.1 2 3 4
- Read the last number. The last number is how many there are.4
- Write the answer. 4
Check. Count them again from the other end. You get 4 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Think about which one keeps a kink.
- Check straw. A plastic straw kinks, and the kink stays.straw
- Check card strip. A card strip bends and springs back a little.card strip
- Write the answer. straw
Check. The straw stays kinked. ✓
Watch out. A card strip is not a straw.
Method. Think about which one bends easily.
- Check wooden block. A thick wooden block changes shape only a little.wooden block
- Check pipe cleaner. A pipe cleaner bends easily and stays bent.pipe cleaner
- Write the answer. pipe cleaner
Check. The pipe cleaner changes shape more. ✓
Watch out. Thick wood is stiff.
Method. Find each number. Then take the smaller number away from the bigger number.
- Read the number for Pipe cleaner. It is 5.Pipe cleaner: 5
- Read the number for Straw. It is 4.Straw: 4
- Take the smaller number away from the bigger one. The difference is how many more.5 − 4 = 1
- Write the answer. 1
Check. Add the difference back on: 4 + 1 = 5. ✓
Watch out. Take the smaller number away from the bigger one, not the other way round.
Method. Find the tallest bar.
- Check straw. The straw bar shows 4.straw
- Check pipe cleaner. The pipe cleaner bar shows 5, the tallest bar.pipe cleaner
- Check card strip. The card strip bar shows 2.card strip
- Write the answer. pipe cleaner
Check. The pipe cleaner bar is the highest. ✓
Watch out. The tallest bar has the most tests.
Method. Think about what a toy snake must do.
- Think about the snake. A toy snake must bend easily.bend easily
- Give the reason. Wood is stiff, so it does not bend much.does not bend much
- Write the answer. it does not bend much
Check. Also accept: it changes shape only a little. ✓
Watch out. Think about which material bends easily.
Method. Make a prediction about thickness.
- Think about thickness. A thin strip is easier to bend than a thick one.thin bends
- Make the prediction. So the thin strip will bend more.yes
- Write the answer. yes
Check. A prediction is a sensible guess that we can check. ✓
Watch out. Test two strips of card the same way, and compare how far each one bends.
Twisting: a wet towel lets water out
When we twist something, we turn one end while the other end stays still.
A wet tea towel can be twisted tight. When we twist it, water is squeezed out.
A pipe cleaner stays twisted when we let go.
A wooden block changes shape only a little when we twist it, so it looks the same.
Key ideas
- Twisting turns one end while the other end stays still.
- Twisting a wet towel squeezes water out.
- A twisted pipe cleaner stays twisted.
- Wood and metal change shape only a little.
Method. Think about what each word means.
- Check bend. Bend means curving something, not turning the ends.bend
- Check twist. Twist means turning one end while the other stays still.twist
- Write the answer. twist
Check. Turning one end is twisting. ✓
Watch out. Bending is curving.
Method. Think about a wet towel being twisted.
- Think about the water. Twisting a wet towel squeezes water out of it.squeezes out
- Write the answer. So water does come out.yes
- Write the answer. yes
Check. Twisting a wet towel lets water out. ✓
Watch out. Only a wet towel has water to squeeze out.
Method. Look at the stripes on each towel.
- Check A. The stripes in A go straight across, so it is not twisted.A
- Check B. The stripes in B slant, so the towel has been twisted.B
- Write the answer. B
Check. Picture B shows a twisted towel. ✓
Watch out. Straight stripes mean no twist.
Watch out
Watch out: twisting a dry towel does not squeeze out water, because there is no water in it.
Try it at home (with a grown-up). Hold each end of a damp tea towel over a bowl or the sink. Twist the two ends in opposite directions, gently. Watch the water drip out. Dry your hands afterwards.
Exam tip
Grown-up tip. Ask: “What comes out when we twist the towel?” Use a bowl or the sink so the floor stays dry. Your child should hold the towel, with you beside them.
Exercise 10D Twisting: a wet towel lets water out
Method. Look at the pipe cleaner.
- Look at the pipe cleaner. Two strands are wound round each other.wound
- Write the answer. So the pipe cleaner has been twisted.yes
- Write the answer. yes
Check. A wound pipe cleaner has been twisted. ✓
Watch out. A straight pipe cleaner has not been twisted.
Method. Make a prediction about a dry towel.
- Think about the towel. A dry towel has no water in it.no water
- Make the prediction. So no water comes out when it is twisted.no
- Write the answer. no
Check. A prediction is a sensible guess that we can check. ✓
Watch out. Try it with a dry towel and a damp one, and compare.
Method. Look at the first picture.
- Look at the towel. Its stripes slant, so it is twisted.slanted
- Write the answer. yes
Check. The towel has been twisted. ✓
Watch out. Slanted stripes mean a twist.
Method. Look at the second picture.
- Look at the straw. It is straight, not twisted.straight
- Write the answer. no
Check. The straw has not been twisted. ✓
Watch out. A straight straw has not been twisted.
Method. Look at the third picture.
- Look at the pipe cleaner. Two strands are wound round each other.wound
- Write the answer. yes
Check. The pipe cleaner has been twisted. ✓
Watch out. Two strands wound together show a twist.
Method. Count the twisted pipe cleaners once each. Touch each one as you count it.
- Count them one at a time. Say each number as you touch one.1 2 3
- Read the last number. The last number is how many there are.3
- Write the answer. 3
Check. Count them again from the other end. You get 3 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Find each count, then add them all together.
- Write down each count. Each count is one row.sponges 5, pipe cleaners 3
- Add the counts together. Add them all, so none is missed.5 + 3 = 8
- Write the answer. 8
Check. Add them again, starting from the last count, and you get 8. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Count the pipe cleaners. Then add 2 for each one.
- Count the pipe cleaners. There are 3 pipe cleaners.3
- Add 2 for each pipe cleaner. Each one is twisted 2 times.2 + 2 + 2
- Write the answer. 6
Check. Count in 2s: there are 3 of them, so the total is 6. ✓
Watch out. Each pipe cleaner counts 2 times.
Method. Think about wood and twisting.
- Read Ben’s idea. Ben says a stick twists easily.twists easily
- Check the idea. Wood changes shape only a little, so Ben is not right.only a little
- Write the answer. no
Check. Ben is not right. Wood does not twist easily. ✓
Watch out. A stiff stick does not twist like a towel.
Method. Think about the two ends of a towel.
- Read the gap. The two ends turn the other way round.other way
- Fill the gap. The two ends turn in opposite directions.opposite
- Write the answer. opposite
Check. Turning in opposite directions is twisting. ✓
Watch out. Same direction would not twist the towel.
Method. Think about a pipe cleaner after twisting.
- Think about the pipe cleaner. A pipe cleaner keeps the twist we give it.keeps twist
- Write the answer. So a twisted pipe cleaner stays twisted.yes
- Write the answer. yes
Check. A pipe cleaner stays twisted. ✓
Watch out. A twisted towel springs back a little when you let go.
Method. Think about a stone and twisting.
- Think about the stone. A stone does not change shape by twisting.no change
- Give the reason. Twisting hard could make it crack or break.could break
- Write the answer. it could break
Check. Also accept: it does not change shape, it could crack. ✓
Watch out. Some things are not made to be twisted, so keep them safe.
Method. Think about a fair test.
- Read the sentence. Tom uses the same number of turns each time.same turns
- Write the word. The number of turns is the thing he keeps the same.turns
- Write the answer. turns
Check. Keeping the turns the same keeps the test fair. ✓
Watch out. Change only one thing at a time.
Stretching: a rubber band springs back, play dough stays long
When we stretch something, we pull it so that it gets longer.
A rubber band stretches when we pull it gently. When we let go, it springs back to its old length.
Play dough stretches too. It stays long when we let go.
Pull gently. A band pulled too hard can snap. Keep the band away from your face and eyes.
Key ideas
- Stretching pulls something so it gets longer.
- A rubber band springs back after a gentle stretch.
- Play dough stays long after we stretch it.
- Never let a stretched band go near your face.
Method. Think about what pulling a band does.
- Look at the band. It is pulled out to be longer.longer
- Write the word. Pulling something to make it longer is stretching.stretch
- Write the answer. stretch
Check. Pulling to make it longer is stretching. ✓
Watch out. Squashing makes things flatter, not longer.
Method. Think about a rubber band after a gentle stretch.
- Think about the band. A gentle stretch lets the band go back to its length.springs back
- Write the answer. So a gently stretched band springs back.yes
- Write the answer. yes
Check. A gentle stretch lets the band spring back. ✓
Watch out. Pulled too hard, a band can snap.
Method. Think about what each one does after you let go.
- Check rubber band. A rubber band springs back to its old length.rubber band
- Check play dough. Play dough stays long after we stretch it.play dough
- Write the answer. play dough
Check. Play dough stays long. ✓
Watch out. A rubber band goes back to its length.
Watch out
Watch out: pulling a rubber band too far can make it snap. Stretch it only a little, and keep it away from your face.
Try it at home (with a grown-up). With a grown-up, stretch a rubber band gently between your two hands, only a little, away from your face and eyes. Let go slowly. Then pull a small piece of play dough into a long shape. Does it stay long?
Exam tip
Grown-up tip. Check the band is not old or dry first. Remind your child to keep it away from the face. Stop if the band looks worn.
Exercise 10E Stretching: a rubber band springs back, play dough stays long
Method. Look at the rubber band.
- Look at the band. It has been pulled longer than a ring.pulled
- Write the answer. So the band is stretched.yes
- Write the answer. yes
Check. A band pulled long is stretched. ✓
Watch out. A ring shape is not stretched.
Method. Think about a band pulled gently.
- Think about the band. A gentle pull lets it go back to its length.back
- Write the answer. springs back
Check. A gently pulled band springs back. ✓
Watch out. Play dough does not spring back.
Method. Think about the play dough.
- Think about the dough. Play dough keeps the shape it is pulled into.keeps
- Write the answer. stays long
Check. Play dough stays long. ✓
Watch out. A band springs back, but dough does not.
Method. Read the sentence and think about play dough.
- Read the gap. The gap is what dough does after we pull it.after pull
- Fill the gap. Play dough stays long after we pull it.stays
- Write the answer. stays
Check. Play dough stays long. ✓
Watch out. Springs back is for rubber bands.
Method. Count the rubber bands once each. Touch each one as you count it.
- Count them one at a time. Say each number as you touch one.1 2 3 4 5
- Read the last number. The last number is how many there are.5
- Write the answer. 5
Check. Count them again from the other end. You get 5 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Find each count, then add them all together.
- Write down each count. Each count is one row.rubber bands 2, play dough 4
- Add the counts together. Add them all, so none is missed.2 + 4 = 6
- Write the answer. 6
Check. Add them again, starting from the last count, and you get 6. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Think about which one can be pulled longer.
- Check rubber band. A rubber band can be pulled longer.rubber band
- Check stone. A stone cannot be pulled longer, so it does not stretch.stone
- Write the answer. rubber band
Check. A rubber band can be stretched. ✓
Watch out. A stone does not stretch.
Method. Think about safety and testing.
- Read Sam’s idea. Sam says to stretch the band until it snaps.snaps
- Check the idea. A band that snaps can hurt, so we stretch it only gently.gently
- Write the answer. no
Check. Sam is not right. Stretch only gently. ✓
Watch out. Never let a band snap near your face.
Method. Each gentle stretch makes one spring back.
- Count the stretches. The band is stretched 4 times.4 stretches
- Each stretch springs back once. So 4 stretches give 4 springs back.4 springs back
- Write the answer. 4
Check. Count the stretches again: 4. ✓
Watch out. Count each gentle stretch once.
Method. Think about a band pulled too hard.
- Think about the band. A band pulled too hard can snap.snap
- Give the reason. A snapping band can hurt the face or eyes.hurt
- Write the answer. it may snap
Check. Also accept: it could snap and hurt you, it could break. ✓
Watch out. Think about what a snapping band could do.
Method. Make a prediction about a gentle stretch.
- Think about the band. A gentle stretch does not break the band.gentle
- Make the prediction. So a gently stretched band will spring back.yes
- Write the answer. yes
Check. A prediction is a sensible guess that we can check. ✓
Watch out. Test with a grown-up. Stretch gently and watch what happens.
Method. Think about what happens to the band.
- Check stretching. Pulling something so it gets longer is stretching.stretching
- Check squashing. Squashing presses something flatter.squashing
- Write the answer. stretching
Check. A band pulled longer is stretched. ✓
Watch out. Squashing makes things flatter.
Fair tests: which material changes shape most?
A fair test changes only one thing at a time. Everything else stays the same.
To find out which material changes shape most, we use the same push for each one, and the same number of tries.
Write your results in a table. Then compare them. Repeat a test to check your results.
The table below shows example results from a class test. The results are made up for this lesson.
| Material | Tests where the shape stayed changed (out of 5) |
|---|---|
| Sponge | 0 |
| Play dough | 5 |
| Wooden block | 0 |
| Straw | 4 |
Key ideas
- A fair test changes only one thing at a time.
- Use the same push for each material.
- Use the same number of tries for each material.
- Record the results in a table, then compare them.
- Repeat a test to check your results.
Method. Think about what a fair test keeps the same.
- Check material. The material is the thing we change, so it is not kept the same.material
- Check push. The push is kept the same, so the test is fair.push
- Write the answer. push
Check. The push stays the same. ✓
Watch out. Change one thing at a time.
| Material | Tests where the shape stayed changed (out of 5) |
|---|---|
| Sponge | 0 |
| Play dough | 5 |
| Wooden block | 0 |
| Straw | 4 |
Method. Start with the total. Take away the number we do not want.
- Start with 5. There are 5 tests in all.5 tests
- Take away 4. 4 are the ones we take away.5 − 4
- Write the answer. The number left is 1.5 − 4 = 1
Check. Add back the ones taken away: 1 + 4 = 5. ✓
Watch out. Subtract to find the tests that did not stay changed. Do not add the two numbers.
| Material | Tests where the shape stayed changed (out of 5) |
|---|---|
| Sponge | 0 |
| Play dough | 5 |
| Wooden block | 0 |
| Straw | 4 |
Method. Find the sponge row. Read the number in it.
- Find the row for Sponge. Go along the row to the number.Sponge: 0
- Check what the number counts. The heading tells you what the number is.0 tests
- Write the answer. That number is the answer.0
Check. Check the number in the table again: 0. ✓
Watch out. Read the number in the table, not the number above it.
Watch out
Watch out: one test is not enough. Test each material again to check the result.
Try it at home (with a grown-up). Put the same small book on top of a sponge, then on a ball of play dough, for one minute each. Take the book off and look at each one. Which one stays changed? Use the same book each time.
Exam tip
Grown-up tip. Ask: “What did we keep the same?” Your child should say the book and the time. Praise any idea, and ask how they could check it.
Exercise 10F Fair tests: which material changes shape most?
Method. Think about what we change in a fair test.
- Check push. The push is kept the same in a fair test.push
- Check material. We change the material on purpose, one at a time.material
- Write the answer. material
Check. We change the material. ✓
Watch out. The push stays the same.
| Material | Tests where the shape stayed changed (out of 5) |
|---|---|
| Sponge | 0 |
| Play dough | 5 |
| Wooden block | 0 |
| Straw | 4 |
Method. Find the row with 5 in the table.
- Check sponge. The sponge row shows 0.sponge
- Check play dough. The play dough row shows 5, so all 5 tests stayed changed.play dough
- Check wooden block. The wooden block row shows 0.wooden block
- Check straw. The straw row shows 4, not 5.straw
- Write the answer. play dough
Check. Play dough stayed changed in all 5 tests. ✓
Watch out. Check each row in the table.
| Material | Tests where the shape stayed changed (out of 5) |
|---|---|
| Sponge | 0 |
| Play dough | 5 |
| Wooden block | 0 |
| Straw | 4 |
Method. Find each number. Then take the smaller number away from the bigger number.
- Read the number for Play dough. It is 5.Play dough: 5
- Read the number for Straw. It is 4.Straw: 4
- Take the smaller number away from the bigger one. The difference is how many more.5 − 4 = 1
- Write the answer. 1
Check. Add the difference back on: 4 + 1 = 5. ✓
Watch out. Take the smaller number away from the bigger one, not the other way round.
| Material | Tests where the shape stayed changed (out of 5) |
|---|---|
| Sponge | 0 |
| Play dough | 5 |
| Wooden block | 0 |
| Straw | 4 |
Method. Read the table for the wooden block.
- Find the wooden block row. It shows 0 tests where the shape stayed changed.0
- Check the idea. Play dough changed most, so Ella is not right.no
- Write the answer. no
Check. Ella is not right. Play dough changed most. ✓
Watch out. Read every row before you decide.
Method. Find the wooden block bar. Read its number.
- Find the row for Wooden block. Go along the row to the number.Wooden block: 0
- Check what the number counts. The heading tells you what the number is.0 tests
- Write the answer. That number is the answer.0
Check. Check the number in the table again: 0. ✓
Watch out. Read the number in the bar chart, not the number above it.
| Material | Tests where the shape stayed changed (out of 5) |
|---|---|
| Sponge | 0 |
| Play dough | 5 |
| Wooden block | 0 |
| Straw | 4 |
Method. Read the title of the table.
- Read the heading. The heading says out of 5, so there were 5 tries each.out of 5
- Write the answer. Each material had 5 tries.5
- Write the answer. 5
Check. Each material had 5 tries. ✓
Watch out. The title tells you how many tries there were.
Method. Think about a fair test.
- Think about the push. The push must stay the same, or the test is not fair.same push
- Write the answer. no
Check. The push must stay the same. ✓
Watch out. Changing the push breaks the test.
Method. Think about a fair test.
- Think about the book. Using the same book keeps the push the same.same book
- Write the answer. yes
Check. The same book keeps the push the same. ✓
Watch out. A different book is a different push.
Method. Think about a fair test.
- Think about two changes. Changing two things at once makes the test unfair.two changes
- Write the answer. no
Check. Change only one thing at a time. ✓
Watch out. Change the material only.
Method. Find each count, then add them all together.
- Write down each count. Each count is one row.sponges 3, play dough 6
- Add the counts together. Add them all, so none is missed.3 + 6 = 9
- Write the answer. 9
Check. Add them again, starting from the last count, and you get 9. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Think about how many things Sam changed.
- Read Sam’s idea. Sam changed two things: the push and the material.two things
- Check the idea. A fair test changes only one thing, so Sam is not right.one thing
- Write the answer. no
Check. Sam is not right. Change only one thing. ✓
Watch out. Change the material, and keep the push the same.
| Material | Tests where the shape stayed changed (out of 5) |
|---|---|
| Sponge | 0 |
| Play dough | 5 |
| Wooden block | 0 |
| Straw | 4 |
Method. Compare the two rows in the table.
- Check straw. The straw row shows 4 tests where it stayed changed.straw
- Check sponge. The sponge row shows 0 tests where it stayed changed.sponge
- Write the answer. straw
Check. The straw stayed changed for more tests. ✓
Watch out. Compare the two numbers.
| Material | Tests where the shape stayed changed (out of 5) |
|---|---|
| Sponge | 0 |
| Play dough | 5 |
| Wooden block | 0 |
| Straw | 4 |
Method. Think about checking a result.
- Think about a test. Doing the test again checks the result.again
- Write the word. Repeating the test checks the results.repeat
- Write the answer. repeat
Check. Repeat a test to check your results. ✓
Watch out. One test is not enough to be sure.
Chapter summary
| Skill | Method |
|---|---|
| Four ways to change shape | Squash, bend, twist and stretch change the shape of some materials. |
| Squashing | Play dough stays squashed. A sponge springs back. |
| Bending | A pipe cleaner stays bent. A straw kinks and the kink stays. |
| Twisting | A wet towel twisted hard lets water out. A twisted pipe cleaner stays twisted. |
| Stretching | A rubber band springs back after a gentle stretch. Play dough stays long. |
| Wood and metal | They change shape only a little when we push, bend or twist them by hand. |
| Fair tests | Change one thing. Keep the push the same. Record results in a table. Repeat the test. |
Can you…?
- I can name the four ways to change shape: squash, bend, twist and stretch
- I can say which materials change shape easily
- I can say whether something springs back or stays changed
- I can plan a fair test that changes only one thing
- I can record fair test results in a table and read them
- I can explain why wood and metal change shape only a little
Key terms
- squash
- to press something so it gets flatter
- bend
- to curve something so it is not straight
- twist
- to turn one end while the other end stays still
- stretch
- to pull something so it gets longer
- spring back
- to go back to the old shape when we let go
- fair test
- a test that changes only one thing at a time
- kink
- a sharp bend that stays in a straw
Exercise 10Z Check-up
Method. Think about curving something.
- Think about the word. Curving something so it is not straight is bending.curve
- Write the word. The word is bend.bend
- Write the answer. bend
Check. Curving something is bending it. ✓
Watch out. Squash means pressing flat.
Method. Think about a sponge.
- Think about the sponge. A sponge goes back to its old shape.springs back
- Write the answer. So a sponge springs back.yes
- Write the answer. yes
Check. A sponge springs back. ✓
Watch out. Play dough stays squashed.
Method. Think about what each one does after you let go.
- Check rubber band. A rubber band springs back.rubber band
- Check play dough. Play dough stays long after it is stretched.play dough
- Write the answer. play dough
Check. Play dough stays long. ✓
Watch out. Rubber bands spring back.
Method. Think about a stone.
- Look at the stone. A stone is hard and does not squash.hard
- Write the answer. So a stone is not easy to squash.no
- Write the answer. no
Check. A stone does not squash. ✓
Watch out. Hard things do not squash easily.
Method. Count the twisted pipe cleaners once each. Touch each one as you count it.
- Count them one at a time. Say each number as you touch one.1 2 3 4
- Read the last number. The last number is how many there are.4
- Write the answer. 4
Check. Count them again from the other end. You get 4 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Find each count, then add them all together.
- Write down each count. Each count is one row.pipe cleaners 3, straws 4
- Add the counts together. Add them all, so none is missed.3 + 4 = 7
- Write the answer. 7
Check. Add them again, starting from the last count, and you get 7. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Think about what twisting needs.
- Read Ali’s idea. Ali says you can twist a towel without turning the ends.no turn
- Check the idea. Twisting needs one end turned while the other stays still.turned
- Write the answer. no
Check. Ali is not right. Twisting needs a turn. ✓
Watch out. Turn one end while the other stays still.
Method. Think about pressing.
- Think about the word. Pressing something so it gets flatter is squashing.flatter
- Write the word. The word is squash.squash
- Write the answer. squash
Check. Pressing flat is squashing. ✓
Watch out. Stretching makes things longer.
Method. Think about a fair test.
- Think about the push. If the push changes, the test is not fair.changes
- Give the reason. Using the same push keeps the test fair.fair
- Write the answer. so the test is fair
Check. Also accept: to keep it fair, so only one thing changes. ✓
Watch out. Change only one thing at a time.
Method. Make a prediction about wood.
- Think about wood. Wood changes shape only a little by hand.a little
- Make the prediction. So a wooden block will not change shape a lot.no
- Write the answer. no
Check. A prediction is a sensible guess that we can check. ✓
Watch out. Test it with a grown-up, and compare wood with a sponge.
Total 13 marks. Allow about 13 minutes.
Exercise 10X End-of-chapter quiz
Method. Think about pressing.
- Think about the word. Pressing something flat is squashing.squash
- Write the word. The word is squash.squash
- Write the answer. squash
Check. Pressing flat is squashing. ✓
Watch out. Stretching makes things longer.
Method. Think about play dough after squashing.
- Think about the dough. Play dough keeps the shape it is pressed into.keeps shape
- Write the answer. So play dough stays squashed.yes
- Write the answer. yes
Check. Play dough stays squashed. ✓
Watch out. A sponge springs back, but dough does not.
Method. Think about what each one does when you let go.
- Check sponge. A sponge goes back to its old shape.sponge
- Check play dough. Play dough stays in the shape it is pressed into.play dough
- Write the answer. sponge
Check. A sponge springs back. ✓
Watch out. Play dough stays squashed.
Method. Count the rubber bands once each. Touch each one as you count it.
- Count them one at a time. Say each number as you touch one.1 2 3 4
- Read the last number. The last number is how many there are.4
- Write the answer. 4
Check. Count them again from the other end. You get 4 again. ✓
Watch out. Move each one to one side as you count it, so you do not count it twice.
Method. Find each count, then add them all together.
- Write down each count. Each count is one row.sponges 3, pipe cleaners 5
- Add the counts together. Add them all, so none is missed.3 + 5 = 8
- Write the answer. 8
Check. Add them again, starting from the last count, and you get 8. ✓
Watch out. Make sure every row is in your total, and no row is counted twice.
Method. Look at the straw.
- Look at the straw. The straw has a curve at a kink.curve
- Write the word. A straw with a curve is bent.bent
- Write the answer. bent
Check. A kinked straw is bent. ✓
Watch out. A straight straw is not bent.
Method. Start with the total. Take away the number we do not want.
- Start with 4. There are 4 straws in all.4 straws
- Take away 2. 2 are the ones we take away.4 − 2
- Write the answer. The number left is 2.4 − 2 = 2
Check. Add back the ones taken away: 2 + 2 = 4. ✓
Watch out. Subtract to find the straws that do not stay kinked. Do not add the two numbers.
Method. Think about a fair test.
- Think about the test. A fair test changes only one thing at a time.one thing
- Check the statement. So the statement is true.true
- Write the answer. true
Check. A fair test changes only one thing. ✓
Watch out. Changing two things makes the test unfair.
Method. Think about a stone.
- Read Sam’s idea. Sam says pressing a stone squashes it.squashes
- Check the idea. A stone is hard and does not squash, so Sam is not right.hard
- Write the answer. no
Check. Sam is not right. A stone does not squash. ✓
Watch out. Hard things do not squash.
Method. Find each number. Then take the smaller number away from the bigger number.
- Read the number for Play dough. It is 5.Play dough: 5
- Read the number for Straw. It is 3.Straw: 3
- Take the smaller number away from the bigger one. The difference is how many more.5 − 3 = 2
- Write the answer. 2
Check. Add the difference back on: 3 + 2 = 5. ✓
Watch out. Take the smaller number away from the bigger one, not the other way round.