2-D and 3-D shapes
By the end of this chapter you will be able to
- Name a flat (2-D) shape and count its straight sides and corners
- Say whether a shape has a vertical line of symmetry
- Name a solid (3-D) shape and count its faces, edges and vertices
- Name the flat (2-D) shape of each face of a solid
- Sort shapes and everyday objects by their shape
You should already know
- Recognising and naming 2-D and 3-D shapes (Year 1, Chapter 3)
- Counting in ones and twos to 20 (Year 1, Chapter 4)
- Adding within 20 (Chapter 2)
Where this leads
- Drawing 2-D shapes and making 3-D shapes; right angles and angles (Year 3)
- Lines of symmetry and reflection with more precision (Year 3)
National Curriculum for England, Key Stage 1 mathematics, Year 2. Content: Identify and describe the properties of 2-D shapes, including the number of sides and line symmetry in a vertical line, Identify and describe the properties of 3-D shapes, including the number of edges, vertices and faces, Identify 2-D shapes on the surface of 3-D shapes, Compare and sort common 2-D and 3-D shapes and everyday objects.
Exercise P Do you remember?
Non-calculatorKey words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a flat (2-D) shape.It is 4 straight sides, all the same length, and 4 corners
- Find the name that matches. Only one shape name has these features.square matches
- Write the name. square
Check. The square has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Method. Think about the shape of the whole object, not one small part.
- Look at the object. Think about its flat parts and curved parts.a ball
- Match it to a shape. A ball is round all over, so it is a sphere.ball = sphere
- Write the name. sphere
Check. Name the flat faces or the curved part to check. ✓
Watch out. Many objects are not perfect shapes, so think about the main shape.
Method. Check the shape of each shape. Then pick the one that matches.
- Look at each shape. Check the shape of each one.A: square has 4 sides; B: circle has 0 sides; C: triangle has 3 sides
- Find the one that matches. A circle is round and has no straight sides.circle matches
- Write the answer. circle
Check. Check each of the other shapes too. Only circle matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Find every sharp point on the outside of the shape. Count each one once.
- Find each corner. A corner is a sharp point where two sides meet.mark each sharp point
- Count the corners. Each corner is counted once.4 corners
- Write the answer. 4
Check. Count the straight sides as well: there are 4. ✓
Watch out. A corner is sharp. A curved part has no corners.
Method. Count the shapes in each group. Then add them together.
- Count the first group. There are 2 shapes.2
- Add the second group. There are 3 more shapes.2 + 3 = 5
- Write the answer. 5
Check. Count all the shapes in the picture once more: 5. ✓
Watch out. Count each shape once. Do not count the same shape twice.
Naming 2-D shapes and counting sides
A 2-D shape is flat. It has length and width, but no depth.
A side is a straight edge. A corner is a sharp point where two sides meet.
A triangle has 3 sides. A square has 4 sides. A pentagon has 5 sides.
A hexagon has 6 sides. A pentagon and a hexagon are shapes with 5 and 6 corners.
A circle and an oval have no straight sides. A semicircle has one straight side and 2 corners.
A square turned on its corner is a diamond. It still has 4 equal sides.
Key ideas
- A triangle has 3 sides.
- A square and a rectangle have 4 sides.
- A pentagon has 5 sides, a hexagon has 6.
- A circle and an oval have no straight sides.
- A semicircle has one straight side and 2 corners.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.3 straight sides
- Write the answer. 3
Check. Count the corners too: there are 3. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Check the number of straight sides of each shape. Then pick the one that matches.
- Look at each shape. Check the number of straight sides of each one.A: square has 4 sides; B: circle has 0 sides; C: triangle has 3 sides
- Find the one that matches. A circle has no straight sides, so it is the answer.circle matches
- Write the answer. circle
Check. Check each of the other shapes too. Only circle matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Find every sharp point on the outside of the shape. Count each one once.
- Find each corner. A corner is a sharp point where two sides meet.mark each sharp point
- Count the corners. Each corner is counted once.2 corners
- Write the answer. 2
Check. Count the straight sides as well: there are 1. ✓
Watch out. A corner is sharp. A curved part has no corners.
Watch out
Watch out: a circle has no sides at all. Its edge is one curve, not a straight side. A semicircle has one straight side, not two.
Exam tip
Grown-up tip. Trace each shape with a finger, round the outside. Say the count out loud: “one side, two sides, three sides.” Then count the corners. A curved part has no corners.
Exercise 8A Naming 2-D shapes and sides
Non-calculatorKey words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a flat (2-D) shape.It is 4 straight sides, all the same length, and 4 corners
- Find the name that matches. Only one shape name has these features.square matches
- Write the name. square
Check. The square has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Key words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a flat (2-D) shape.It is 4 straight sides, two long and two short, and 4 corners
- Find the name that matches. Only one shape name has these features.rectangle matches
- Write the name. rectangle
Check. The rectangle has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.3 straight sides
- Write the answer. 3
Check. Count the corners too: there are 3. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.6 straight sides
- Write the answer. 6
Check. Count the corners too: there are 6. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.5 straight sides
- Write the answer. 5
Check. Count the corners too: there are 5. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.4 straight sides
- Write the answer. 4
Check. Count the corners too: there are 4. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.3 straight sides
- Write the answer. 3
Check. Count the corners too: there are 3. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.5 straight sides
- Write the answer. 5
Check. Count the corners too: there are 5. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Check the number of sides of each shape. Then pick the one that matches.
- Look at each shape. Check the number of sides of each one.A: square has 4 sides; B: hexagon has 6 sides; C: triangle has 3 sides
- Find the one that matches. Only the hexagon has 6 sides.hexagon matches
- Write the answer. hexagon
Check. Check each of the other shapes too. Only hexagon matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Check the sides of each shape. Then pick the one that matches.
- Look at each shape. Check the sides of each one.A: rectangle has two long and two short sides; B: triangle has 3 sides; C: square has 4 equal sides; D: pentagon has 5 sides
- Find the one that matches. Only the square has 4 sides that are all the same length.square matches
- Write the answer. square
Check. Check each of the other shapes too. Only square matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Look at the edge of the circle.
- Trace the edge. The edge is round all the way round.curved only
- Look for straight sides. A circle has no straight sides.straight sides: 0
- Write the answer. No
Check. A circle has 0 straight sides, so the answer is No. ✓
Watch out. A curved edge is not a straight side.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Every part of the edge is curved.curved all the way round
- Count the straight sides. There are no straight sides to count.0 straight sides
- Write the answer. 0
Check. A shape with no straight sides has no corners either. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.1 straight sides
- Write the answer. 1
Check. Count the corners too: there are 2. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Every part of the edge is curved.curved all the way round
- Count the straight sides. There are no straight sides to count.0 straight sides
- Write the answer. 0
Check. A shape with no straight sides has no corners either. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.4 straight sides
- Write the answer. 4
Check. Count the corners too: there are 4. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.1 straight sides
- Write the answer. 1
Check. Count the corners too: there are 2. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Method. A diamond is a square turned on its corner.
- Count the sides. A diamond has 4 straight sides.4 sides
- Check if they are equal. All 4 sides are the same length, the same as a square.4 equal sides
- Decide. So a diamond is a square turned round, and Mia is not right.No
Check. Turn the diamond back and it is a square with 4 equal sides. ✓
Watch out. A shape is still the same shape when it is turned round.
Method. Count all the straight sides of the rectangle.
- Trace the edge with your finger. Go all the way round the rectangle.top, right, bottom, left
- Count the sides. A rectangle has 4 straight sides, not 2.4 sides
- Decide. Ali forgot the two short sides, so he is not right.No
Check. 4 sides is more than 2, so Ali is not right. ✓
Watch out. A rectangle has 4 sides: 2 long and 2 short.
Vertical lines of symmetry
A shape has a line of symmetry if you can fold it so that the two halves match.
In this chapter we look at a vertical line. It goes straight up and down through the middle.
A square has a vertical line of symmetry. A triangle standing up has one too.
A shape turned on its side may not fold up and down. Then it has no vertical line of symmetry.
Key ideas
- A line of symmetry folds a shape into two matching halves.
- A vertical line goes straight up and down.
- Turn a shape round in your head to check the fold.
- A sideways or slanting line is not a vertical line.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves do not match.Do the two halves match?
- Write the answer. No
Check. The shape is turned, so its line of symmetry slopes or goes sideways. A vertical fold does not match.
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Look for a straight up-and-down fold line where the two halves match.
- Look for a vertical fold line. Draw it straight up and down through the middle.one vertical line
- Check the fold. The two halves match, so the line is a line of symmetry.halves match
- Write the answer. 1
Check. There is only one vertical direction, so only one vertical line can be a line of symmetry. ✓
Watch out. A shape can have other lines of symmetry. Only the up-and-down line counts here.
Watch out
Watch out: a shape can have other lines of symmetry, which slope or go sideways. In this section we only look at the line that goes straight up and down.
Exam tip
Grown-up tip. Cut out a paper shape and fold it in half, straight up and down. If the two halves match, the fold is a vertical line of symmetry. Try the same shape turned on its side.
Exercise 8B Vertical lines of symmetry
Non-calculatorMethod. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves do not match.Do the two halves match?
- Write the answer. No
Check. The shape is turned, so its line of symmetry slopes or goes sideways. A vertical fold does not match.
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves do not match.Do the two halves match?
- Write the answer. No
Check. The shape is turned, so its line of symmetry slopes or goes sideways. A vertical fold does not match.
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves do not match.Do the two halves match?
- Write the answer. No
Check. The shape is turned, so its line of symmetry slopes or goes sideways. A vertical fold does not match.
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Check each shape for a vertical fold. Keep the ones where the halves match.
- Check shape A. The square folds up and down, and the halves match.A: yes
- Check shape B. The triangle is on its side, so the halves do not match.B: no
- Check shape C. The rectangle is tilted, so the halves do not match.C: no
- Check shape D. The oval folds up and down, and the halves match.D: yes
- Write the letters. A and D
Check. Each letter with a yes has halves that match along a vertical fold. ✓
Watch out. Turn the shape in your head. A turned shape often has a sideways fold.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Look for a straight up-and-down fold line where the two halves match.
- Look for a vertical fold line. Draw it straight up and down through the middle.one vertical line
- Check the fold. The two halves match, so the line is a line of symmetry.halves match
- Write the answer. 1
Check. There is only one vertical direction, so only one vertical line can be a line of symmetry. ✓
Watch out. A shape can have other lines of symmetry. Only the up-and-down line counts here.
Method. Check a shape that is not a circle.
- Look at the square. The square folds up and down, and the halves match.square: yes
- Compare with Mia. The square is not a circle, but it has a vertical line of symmetry.not only circles
- Decide. Mia is not right.No
Check. A rectangle, an oval and a triangle standing up also have one. ✓
Watch out. Many shapes have a vertical line of symmetry, not only circles.
Faces, edges and vertices of 3-D shapes
A 3-D shape is solid. It has length, width and depth.
A face is a flat surface. An edge is a straight line where two faces meet.
A vertex is a corner. More than one vertex is vertices.
A cube has 6 faces, 12 edges and 8 vertices.
A sphere has no flat faces, no edges and no vertices.
Key ideas
- A face is a flat surface.
- An edge is a straight line where two faces meet.
- A vertex is a corner.
- A cube has 6 faces, 12 edges and 8 vertices.
Method. Count the flat faces of the cube. Count the ones you cannot see, like the bottom.
- Look at the shape. A face is a flat surface.a cube
- Count the flat faces. There are 6 flat faces on a cube.6 flat faces
- Write the answer. 6
Check. Faces plus vertices equals edges plus 2: 6 + 8 = 12 + 2. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the vertices (corners) of the cuboid. Count the ones you cannot see, like the bottom.
- Look at the shape. A vertex is a sharp corner point.a cuboid
- Count the vertices (corners). There are 8 vertices (corners) on a cuboid.8 vertices (corners)
- Write the answer. 8
Check. Faces plus vertices equals edges plus 2: 6 + 8 = 12 + 2. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the edges of the pyramid. Count the ones you cannot see, like the bottom.
- Look at the shape. An edge is a straight line where two faces meet.a pyramid
- Count the edges. There are 6 edges on a pyramid.6 edges
- Write the answer. 6
Check. Faces plus vertices equals edges plus 2: 4 + 4 = 6 + 2. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Watch out
Watch out: a face is flat. The curved side of a cylinder is not a flat face, and a sphere has no flat faces.
Exam tip
Grown-up tip. Use a cereal box. Count the faces first, then the edges, then the corners. Run your finger along each edge. Ask: “How many corners can you find?”
Exercise 8C 3-D shapes: faces, edges and vertices
Non-calculatorKey words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a solid (3-D) shape.It is a box with 6 equal square faces
- Find the name that matches. Only one shape name has these features.cube matches
- Write the name. cube
Check. The cube has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Key words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a solid (3-D) shape.It is a ball with no flat faces, no edges and no corners
- Find the name that matches. Only one shape name has these features.sphere matches
- Write the name. sphere
Check. The sphere has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Key words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a solid (3-D) shape.It is a round flat base and one point at the top
- Find the name that matches. Only one shape name has these features.cone matches
- Write the name. cone
Check. The cone has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Key words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a solid (3-D) shape.It is 2 flat circle ends and a curved side
- Find the name that matches. Only one shape name has these features.cylinder matches
- Write the name. cylinder
Check. The cylinder has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Method. Count the flat faces of the cuboid. Count the ones you cannot see, like the bottom.
- Look at the shape. A face is a flat surface.a cuboid
- Count the flat faces. There are 6 flat faces on a cuboid.6 flat faces
- Write the answer. 6
Check. Faces plus vertices equals edges plus 2: 6 + 8 = 12 + 2. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the edges of the cube. Count the ones you cannot see, like the bottom.
- Look at the shape. An edge is a straight line where two faces meet.a cube
- Count the edges. There are 12 edges on a cube.12 edges
- Write the answer. 12
Check. Faces plus vertices equals edges plus 2: 6 + 8 = 12 + 2. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the vertices (corners) of the cube. Count the ones you cannot see, like the bottom.
- Look at the shape. A vertex is a sharp corner point.a cube
- Count the vertices (corners). There are 8 vertices (corners) on a cube.8 vertices (corners)
- Write the answer. 8
Check. Faces plus vertices equals edges plus 2: 6 + 8 = 12 + 2. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the flat faces of the cylinder. Count the ones you cannot see, like the bottom.
- Look at the shape. A face is a flat surface.a cylinder
- Count the flat faces. There are 2 flat faces on a cylinder.2 flat faces
- Write the answer. 2
Check. A curved surface is not a flat face, and its curved rim is not a straight edge, so it is not counted. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the vertices (corners) of the cylinder. Count the ones you cannot see, like the bottom.
- Look at the shape. A vertex is a sharp corner point.a cylinder
- Count the vertices (corners). There are 0 vertices (corners) on a cylinder.0 vertices (corners)
- Write the answer. 0
Check. A curved surface is not a flat face, and its curved rim is not a straight edge, so it is not counted. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the flat faces of the pyramid. Count the ones you cannot see, like the bottom.
- Look at the shape. A face is a flat surface.a pyramid
- Count the flat faces. There are 4 flat faces on a pyramid.4 flat faces
- Write the answer. 4
Check. Faces plus vertices equals edges plus 2: 4 + 4 = 6 + 2. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the flat faces of the cone. Count the ones you cannot see, like the bottom.
- Look at the shape. A face is a flat surface.a cone
- Count the flat faces. There are 1 flat faces on a cone.1 flat faces
- Write the answer. 1
Check. A curved surface is not a flat face, and its curved rim is not a straight edge, so it is not counted. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the vertices (corners) of the cone. Count the ones you cannot see, like the bottom.
- Look at the shape. A vertex is a sharp corner point.a cone
- Count the vertices (corners). There are 1 vertices (corners) on a cone.1 vertices (corners)
- Write the answer. 1
Check. A curved surface is not a flat face, and its curved rim is not a straight edge, so it is not counted. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Check the faces, edges and vertices of each shape. Then pick the one that matches.
- Look at each shape. Check the faces, edges and vertices of each one.A: cube has 6 flat faces; B: sphere has no flat faces, edges or vertices; C: cone has one flat face
- Find the one that matches. Only the sphere has no flat faces, no edges and no vertices.sphere matches
- Write the answer. sphere
Check. Check each of the other shapes too. Only sphere matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Check the number of vertices of each shape. Then pick the one that matches.
- Look at each shape. Check the number of vertices of each one.A: cube has 8 vertices; B: pyramid has 4 vertices; C: cylinder has 0 vertices
- Find the one that matches. Only the cube has 8 vertices.cube matches
- Write the answer. cube
Check. Check each of the other shapes too. Only cube matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Count the faces and the edges of the cylinder.
- Count the faces. A cylinder has 2 flat circle ends.2 flat faces
- Count the edges. Its rims are curved, so there are no straight edges.0 edges
- Decide. Sam says 1 edge, but there are none, so he is not right.No
Check. Faces: 2. Straight edges: 0. Sam is not right. ✓
Watch out. A curved rim is not a straight edge.
2-D shapes on the faces of 3-D shapes
Solid shapes have faces. Each flat face is a 2-D shape.
A cube has 6 square faces. A cuboid has rectangle faces.
A cylinder has 2 flat ends. Each end is a circle.
A pyramid with a triangle base has triangle faces.
A sphere has no flat faces, so no 2-D shape is on it.
Key ideas
- A cube has 6 square faces.
- A cuboid has rectangle faces.
- A cylinder has 2 circle ends.
- A pyramid has triangle faces.
- A sphere has no flat faces.
Method. Look at one flat face of the cube. Then name its shape.
- Look at one flat face. A cube has flat faces that are squares.one flat face of the cube
- Check its sides. Count the straight sides, or check if the face is round.4 equal straight sides
- Name the shape. This flat face is a square.square
Check. Every flat face of this cube is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at one flat face of the cylinder. Then name its shape.
- Look at one flat face. A cylinder has flat faces that are circles.one flat face of the cylinder
- Check its sides. Count the straight sides, or check if the face is round.round, with no straight sides
- Name the shape. This flat face is a circle.circle
Check. Every flat face of this cylinder is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at one flat face of the pyramid. Then name its shape.
- Look at one flat face. A pyramid has flat faces that are triangles.one flat face of the pyramid
- Check its sides. Count the straight sides, or check if the face is round.3 straight sides
- Name the shape. This flat face is a triangle.triangle
Check. Every flat face of this pyramid is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Watch out
Watch out: a face of a cube is a square, not a cube. A cube is 3-D. A square is 2-D. The curved side of a cylinder is not a flat 2-D shape.
Exam tip
Grown-up tip. Find a box, a tin and a ball at home. Ask: “What shape is the flat side?” Then ask: “Does the ball have a flat side?”
Exercise 8D 2-D shapes on the faces of 3-D shapes
Non-calculatorMethod. Look at one flat face of the cube. Then name its shape.
- Look at one flat face. A cube has flat faces that are squares.one flat face of the cube
- Check its sides. Count the straight sides, or check if the face is round.4 equal straight sides
- Name the shape. This flat face is a square.square
Check. Every flat face of this cube is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at one flat face of the cuboid. Then name its shape.
- Look at one flat face. A cuboid has flat faces that are rectangles.one flat face of the cuboid
- Check its sides. Count the straight sides, or check if the face is round.4 straight sides, two long and two short
- Name the shape. This flat face is a rectangle.rectangle
Check. Every flat face of this cuboid is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at one flat face of the cylinder. Then name its shape.
- Look at one flat face. A cylinder has flat faces that are circles.one flat face of the cylinder
- Check its sides. Count the straight sides, or check if the face is round.round, with no straight sides
- Name the shape. This flat face is a circle.circle
Check. Every flat face of this cylinder is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at one flat face of the pyramid. Then name its shape.
- Look at one flat face. A pyramid has flat faces that are triangles.one flat face of the pyramid
- Check its sides. Count the straight sides, or check if the face is round.3 straight sides
- Name the shape. This flat face is a triangle.triangle
Check. Every flat face of this pyramid is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at one flat face of the cone. Then name its shape.
- Look at one flat face. A cone has flat faces that are circles.one flat face of the cone
- Check its sides. Count the straight sides, or check if the face is round.round, with no straight sides
- Name the shape. This flat face is a circle.circle
Check. Every flat face of this cone is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Check the shape of a face of each shape. Then pick the one that matches.
- Look at each shape. Check the shape of a face of each one.A: triangle; B: square; C: circle
- Find the one that matches. A cube has square faces, so B is the answer.B matches
- Write the answer. B
Check. Check each of the other shapes too. Only B matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Check the shape of a face of each shape. Then pick the one that matches.
- Look at each shape. Check the shape of a face of each one.A: circle; B: rectangle; C: triangle
- Find the one that matches. A cuboid has rectangle faces, so B is the answer.B matches
- Write the answer. B
Check. Check each of the other shapes too. Only B matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Check the shape of the flat end of each shape. Then pick the one that matches.
- Look at each shape. Check the shape of the flat end of each one.A: triangle; B: square; C: circle
- Find the one that matches. A cylinder has circle ends, so C is the answer.C matches
- Write the answer. C
Check. Check each of the other shapes too. Only C matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Look at one flat face of the cylinder. Then name its shape.
- Look at one flat face. A cylinder has flat faces that are circles.one flat face of the cylinder
- Check its sides. Count the straight sides, or check if the face is round.round, with no straight sides
- Name the shape. This flat face is a circle.circle
Check. Every flat face of this cylinder is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at one flat face of the cube. Then name its shape.
- Look at one flat face. A cube has flat faces that are squares.one flat face of the cube
- Check its sides. Count the straight sides, or check if the face is round.4 equal straight sides
- Name the shape. This flat face is a square.square
Check. Every flat face of this cube is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at one flat face of the cuboid. Then name its shape.
- Look at one flat face. A cuboid has flat faces that are rectangles.one flat face of the cuboid
- Check its sides. Count the straight sides, or check if the face is round.4 straight sides, two long and two short
- Name the shape. This flat face is a rectangle.rectangle
Check. Every flat face of this cuboid is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at the surface of the sphere.
- Look for a flat part. The whole surface of a sphere is curved.curved all over
- Decide. A sphere has no flat faces.flat faces: 0
- Write the answer. No
Check. A sphere has 0 flat faces. ✓
Watch out. A ball rolls because it has no flat faces.
Method. Check the shape of the faces of each shape. Then pick the one that matches.
- Look at each shape. Check the shape of the faces of each one.A: cube has square faces; B: pyramid has triangle faces; C: cuboid has rectangle faces
- Find the one that matches. Only the pyramid has triangle faces.pyramid matches
- Write the answer. pyramid
Check. Check each of the other shapes too. Only pyramid matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Look at the faces of the cube.
- Look at one face. Each face of a cube is a square.square
- Check the others. All 6 faces of a cube are squares.6 squares
- Decide. Ben is not right.No
Check. A square has 4 sides, not 3, so it is not a triangle. ✓
Watch out. A triangle has 3 sides. A square has 4.
Method. Check the number of flat circle faces of each shape. Then pick the one that matches.
- Look at each shape. Check the number of flat circle faces of each one.A: cone has 1 flat circle base; B: cylinder has 2 flat circle ends
- Find the one that matches. Only the cylinder has 2 flat circle ends.cylinder matches
- Write the answer. cylinder
Check. Check each of the other shapes too. Only cylinder matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Think about the faces of a box.
- Look at the faces. All 6 faces are the same square.6 square faces
- Think about the edges. When all faces are squares, all the edges are the same length.all edges equal
- Decide. That shape is a cube, so the answer is Yes.Yes
Check. A cube has 6 square faces and 12 edges that are all the same length. ✓
Watch out. A cuboid has rectangle faces, so it is not always square.
Comparing and sorting shapes and everyday objects
We can sort shapes into groups. We can sort them by flat or solid.
We can also sort them by sides, corners, faces or vertices.
A ball is shaped like a sphere. A tin is shaped like a cylinder.
A book is shaped like a cuboid. A clock face is a flat circle.
Key ideas
- Flat shapes are 2-D. Solid shapes are 3-D.
- Sort shapes by their sides, corners, faces and vertices.
- A ball is a sphere. A tin is a cylinder.
- A book is a cuboid.
Method. Check the flat or solid of each shape. Then pick the one that matches.
- Look at each shape. Check the flat or solid of each one.A: square is flat; B: cube is solid; C: circle is flat
- Find the one that matches. A cube has depth, so it is solid. The square and circle are flat.B matches
- Write the answer. B
Check. Check each of the other shapes too. Only B matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Count the sides of each shape. Then compare the two numbers.
- Count the sides of triangle. The triangle has 3 sides.triangle: 3
- Count the sides of pentagon. The pentagon has 5 sides.pentagon: 5
- Compare the numbers. The shape with more sides is the answer.5 is more than 3
- Write the answer. pentagon
Check. The other shape has more sides, so pentagon is right. ✓
Watch out. Count both shapes before you decide.
Method. Think about the shape of the whole object, not one small part.
- Look at the object. Think about its flat parts and curved parts.a tin
- Match it to a shape. A tin has 2 flat circle ends and a curved side, so it is a cylinder.tin = cylinder
- Write the name. cylinder
Check. Name the flat faces or the curved part to check. ✓
Watch out. Many objects are not perfect shapes, so think about the main shape.
Watch out
Watch out: a book is not a cube. A book has rectangle faces, not square faces.
Exam tip
Grown-up tip. Gather a ball, a tin, a box and a block from home. Ask: “Which one can roll?” and “Which one has flat faces?”
Exercise 8E Comparing and sorting shapes and objects
Non-calculatorMethod. A flat shape has length and width, but no depth.
- Look at the shape. It is drawn flat, on the page.length and width only
- Decide. A flat shape is 2-D.flat
- Write the answer. flat
Check. A triangle is 2-D, so it is flat. ✓
Watch out. A solid shape has depth, like a box.
Method. A solid shape has depth, so you can pick it up.
- Look at the shape. It has length, width and depth.a box with depth
- Decide. A solid shape is 3-D.solid
- Write the answer. solid
Check. A cuboid has depth, so it is solid. ✓
Watch out. A flat shape has no depth.
Method. Check the flat or solid of each shape. Then pick the one that matches.
- Look at each shape. Check the flat or solid of each one.A: circle is flat; B: sphere is solid; C: square is flat
- Find the one that matches. A sphere has depth, so it is solid. The circle and square are flat.B matches
- Write the answer. B
Check. Check each of the other shapes too. Only B matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Count the sides of each shape. Then compare the two numbers.
- Count the sides of square. The square has 4 sides.square: 4
- Count the sides of triangle. The triangle has 3 sides.triangle: 3
- Compare the numbers. The shape with more sides is the answer.4 is more than 3
- Write the answer. square
Check. The other shape has more sides, so square is right. ✓
Watch out. Count both shapes before you decide.
Method. Count the corners of each shape. Then compare the two numbers.
- Count the corners of circle. The circle has 0 corners.circle: 0
- Count the corners of hexagon. The hexagon has 6 corners.hexagon: 6
- Compare the numbers. The shape with fewer corners is the answer.0 is fewer than 6
- Write the answer. circle
Check. The other shape has fewer corners, so circle is right. ✓
Watch out. Count both shapes before you decide.
Method. Check the number of sides of each shape. Then pick the one that matches.
- Look at each shape. Check the number of sides of each one.A: square has 4 sides; B: pentagon has 5 sides; C: triangle has 3 sides
- Find the one that matches. The pentagon has the most sides, 5.pentagon matches
- Write the answer. pentagon
Check. Check each of the other shapes too. Only pentagon matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Think about the shape of the whole object, not one small part.
- Look at the object. Think about its flat parts and curved parts.a ball
- Match it to a shape. A ball is round all over, so it is a sphere.ball = sphere
- Write the name. sphere
Check. Name the flat faces or the curved part to check. ✓
Watch out. Many objects are not perfect shapes, so think about the main shape.
Method. Think about the shape of the whole object, not one small part.
- Look at the object. Think about its flat parts and curved parts.a tin
- Match it to a shape. A tin has 2 flat circle ends and a curved side, so it is a cylinder.tin = cylinder
- Write the name. cylinder
Check. Name the flat faces or the curved part to check. ✓
Watch out. Many objects are not perfect shapes, so think about the main shape.
Method. Think about the shape of the whole object, not one small part.
- Look at the object. Think about its flat parts and curved parts.a book
- Match it to a shape. A book has 6 flat rectangle faces, so it is a cuboid.book = cuboid
- Write the name. cuboid
Check. Name the flat faces or the curved part to check. ✓
Watch out. Many objects are not perfect shapes, so think about the main shape.
Method. Think about the shape of the whole object, not one small part.
- Look at the object. Think about its flat parts and curved parts.a ball
- Match it to a shape. A ball is round all over, so it is a sphere.ball = sphere
- Write the name. sphere
Check. Name the flat faces or the curved part to check. ✓
Watch out. Many objects are not perfect shapes, so think about the main shape.
Method. Think about the shape of the whole object, not one small part.
- Look at the object. Think about its flat parts and curved parts.a tin
- Match it to a shape. A tin has 2 flat circle ends and a curved side, so it is a cylinder.tin = cylinder
- Write the name. cylinder
Check. Name the flat faces or the curved part to check. ✓
Watch out. Many objects are not perfect shapes, so think about the main shape.
Method. Think about the shape of the whole object, not one small part.
- Look at the object. Think about its flat parts and curved parts.a cube
- Match it to a shape. This block has 6 equal square faces, so it is a cube.cube = cube
- Write the name. cube
Check. Name the flat faces or the curved part to check. ✓
Watch out. Many objects are not perfect shapes, so think about the main shape.
Method. A curved surface has no flat face on it. Check each shape.
- Check shape A. The cube has only flat square faces.A: flat only
- Check shape B. The sphere is curved all over.B: curved
- Check shape C. The cylinder has a curved side.C: curved
- Check shape D. The pyramid has only flat triangle faces.D: flat only
- Write the letters. B and C
Check. The sphere and the cylinder are the only shapes with a curved surface here. ✓
Watch out. Look at the whole surface. A shape with any curved part has a curved surface.
Method. Count the corners of each shape. Then compare the two numbers.
- Count the corners of circle. The circle has 0 corners.circle: 0
- Count the corners of square. The square has 4 corners.square: 4
- Compare the numbers. The shape with fewer corners is the answer.0 is fewer than 4
- Write the answer. circle
Check. The other shape has fewer corners, so circle is right. ✓
Watch out. Count both shapes before you decide.
Method. Count the corners of the cuboid, the same as the vertices.
- Look at the cuboid. It is a box with a corner at each end of each edge.corners on each end
- Count the corners. A cuboid has 8 vertices.8 corners
- Decide. It has more than the rectangle. Ruby is not right.No
Check. 8 corners is not 4 corners, so Ruby is not right. ✓
Watch out. A rectangle is flat, with 4 corners. A cuboid is solid, with 8.
Method. Look at each shape. Think about flat and solid.
- Check each shape. The square, triangle and circle are flat (2-D).flat: square, triangle, circle
- Find the different one. The cube is solid (3-D). It is the odd one out.solid: cube
- Write the answer. cube
Check. Only the cube is solid. ✓
Watch out. Check whether each shape is flat or solid before you compare.
Chapter summary
| Skill | Method |
|---|---|
| 2-D shapes | A flat shape has length and width. A side is a straight edge. A corner is a sharp point. |
| Sides | Triangle 3, square 4, rectangle 4, pentagon 5, hexagon 6. A circle or an oval has no straight sides. |
| Vertical line of symmetry | The two halves match when folded along a straight up-and-down line. |
| 3-D shapes | A face is flat. An edge is a straight line where faces meet. A vertex is a corner. |
| Cube and cuboid | Each has 6 faces, 12 edges and 8 vertices. |
| 2-D shapes on 3-D shapes | A cube has square faces. A cuboid has rectangle faces. A cylinder has circle ends. |
| Sorting | Sort shapes by flat or solid, by sides, or by curved surfaces. A ball is a sphere; a tin is a cylinder. |
Can you…?
- I can name a 2-D shape and count its sides.
- I can say whether a shape has a vertical line of symmetry.
- I know that a circle and an oval have no straight sides.
- I can name a 3-D shape.
- I can count the faces, edges and vertices of a cube.
- I can name the 2-D shape of a face of a 3-D shape.
- I can sort shapes and everyday objects by their shape.
Key terms
- 2-D shape
- a flat shape with length and width, but no depth.
- 3-D shape
- a solid shape with length, width and depth.
- side
- a straight edge of a flat shape.
- corner
- a sharp point where two sides of a flat shape meet.
- line of symmetry
- a line where a shape folds so that the two halves match.
- vertical
- straight up and down.
- face
- a flat surface of a solid shape.
- edge
- a straight line where two faces of a solid shape meet.
- vertex
- a corner of a solid shape. More than one is vertices.
- cube
- a solid shape with 6 equal square faces.
- cuboid
- a solid box shape with 6 rectangle faces.
- sphere
- a round solid shape, like a ball, with no flat faces.
- cylinder
- a solid shape with 2 flat circle ends and a curved side.
- cone
- a solid shape with a round flat base and one point at the top.
- pyramid
- a solid shape with a flat base and triangle faces that meet at a point.
Exercise 8Z Check-up
Non-calculatorKey words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a flat (2-D) shape.It is 6 straight sides and 6 corners
- Find the name that matches. Only one shape name has these features.hexagon matches
- Write the name. hexagon
Check. The hexagon has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Method. Trace each straight side with your finger, and count it once.
- Trace the edge with your finger. Go round the outside of the shape once.one trip round the shape
- Count the straight sides. Count each straight side once.5 straight sides
- Write the answer. 5
Check. Count the corners too: there are 5. ✓
Watch out. A curved edge is not a side. Count only the straight parts.
Key words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a solid (3-D) shape.It is a flat triangle base and 3 triangle sides that meet at a point
- Find the name that matches. Only one shape name has these features.pyramid matches
- Write the name. pyramid
Check. The pyramid has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Method. Count the flat faces of the cube. Count the ones you cannot see, like the bottom.
- Look at the shape. A face is a flat surface.a cube
- Count the flat faces. There are 6 flat faces on a cube.6 flat faces
- Write the answer. 6
Check. Faces plus vertices equals edges plus 2: 6 + 8 = 12 + 2. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Count the vertices (corners) of the cuboid. Count the ones you cannot see, like the bottom.
- Look at the shape. A vertex is a sharp corner point.a cuboid
- Count the vertices (corners). There are 8 vertices (corners) on a cuboid.8 vertices (corners)
- Write the answer. 8
Check. Faces plus vertices equals edges plus 2: 6 + 8 = 12 + 2. ✓
Watch out. Turn the shape in your mind. Hidden faces, like the base, still count.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves do not match.Do the two halves match?
- Write the answer. No
Check. The shape is turned, so its line of symmetry slopes or goes sideways. A vertical fold does not match.
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Look at one flat face of the cylinder. Then name its shape.
- Look at one flat face. A cylinder has flat faces that are circles.one flat face of the cylinder
- Check its sides. Count the straight sides, or check if the face is round.round, with no straight sides
- Name the shape. This flat face is a circle.circle
Check. Every flat face of this cylinder is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Check the shape of each shape. Then pick the one that matches.
- Look at each shape. Check the shape of each one.A: cone has a point and a round flat base; B: cylinder has 2 flat ends; C: sphere has no flat faces
- Find the one that matches. Only the cone has a point at the top and a round flat base.cone matches
- Write the answer. cone
Check. Check each of the other shapes too. Only cone matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Check the flat or solid of each shape. Then pick the one that matches.
- Look at each shape. Check the flat or solid of each one.A: cube is solid; B: circle is flat; C: cuboid is solid
- Find the one that matches. A circle has no depth, so it is flat. The cube and cuboid are solid.B matches
- Write the answer. B
Check. Check each of the other shapes too. Only B matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. A square turned on its corner is still a square.
- Look at the diamond. It has 4 straight sides, all the same length.4 equal sides
- Think about turning. Turning a shape round does not change it.same shape turned
- Decide. Sam is not right.No
Check. A diamond is a square turned on its corner. ✓
Watch out. A shape is still the same shape when it is turned.
Total 13 marks. Allow about 13 minutes.
Exercise 8X End-of-chapter quiz
Non-calculatorKey words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a flat (2-D) shape.It is 5 straight sides and 5 corners
- Find the name that matches. Only one shape name has these features.pentagon matches
- Write the name. pentagon
Check. The pentagon has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Key words. A flat shape is 2-D. A solid shape is 3-D, so it has depth.
Method. Look at the shape. Think about its sides or faces, then match them to a name.
- Look at the shape. It is a solid (3-D) shape.It is 2 flat circle ends and a curved side
- Find the name that matches. Only one shape name has these features.cylinder matches
- Write the name. cylinder
Check. The cylinder has the features we looked for. ✓
Watch out. Look at the whole shape before you name it. Do not guess from one part.
Method. Find every sharp point on the outside of the shape. Count each one once.
- Find each corner. A corner is a sharp point where two sides meet.mark each sharp point
- Count the corners. Each corner is counted once.2 corners
- Write the answer. 2
Check. Count the straight sides as well: there are 1. ✓
Watch out. A corner is sharp. A curved part has no corners.
Method. Count the faces of the cube.
- Count the faces. A cube has 6 faces.6 faces
- Compare with Ali. Ali says 8, which is 2 more.8 is not 6
- Decide. Ali is not right.No
Check. A cube has 6 faces and 8 vertices. Ali mixed up the vertices. ✓
Watch out. Faces and vertices are different. Check which one you are counting.
Method. Check the number of straight sides of each shape. Then pick the one that matches.
- Look at each shape. Check the number of straight sides of each one.A: triangle has 3 sides; B: oval has 0 sides
- Find the one that matches. An oval has no straight sides.oval matches
- Write the answer. oval
Check. Check each of the other shapes too. Only oval matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.
Method. Look at one flat face of the cuboid. Then name its shape.
- Look at one flat face. A cuboid has flat faces that are rectangles.one flat face of the cuboid
- Check its sides. Count the straight sides, or check if the face is round.4 straight sides, two long and two short
- Name the shape. This flat face is a rectangle.rectangle
Check. Every flat face of this cuboid is the same kind of shape. ✓
Watch out. A face is flat, so it is a 2-D shape. The solid itself is 3-D.
Method. Look at each side of the diamond.
- Look at the sides. All the sides of a diamond are the same length.all 4 equal
- Count the equal sides. There are 4 sides, and they are all the same.4 equal sides
- Write the answer. 4
Check. A diamond has 4 straight sides, so all 4 are equal. ✓
Watch out. The number of equal sides is the number of sides here.
Method. Check the number of vertices of each shape. Then pick the one that matches.
- Look at each shape. Check the number of vertices of each one.A: cube has 8 vertices; B: pyramid has 4 vertices
- Find the one that matches. Only the cube has 8 vertices.cube matches
- Write the answer. cube
Check. Check each of the other shapes too. Only cube matches. ✓
Watch out. Check every shape, not only the first one you see.
Method. Imagine folding the shape in half, down the middle from top to bottom.
- Imagine a vertical fold. The fold line goes straight up and down.a straight up-and-down fold
- Check the two halves. Folded along a straight up-and-down line, the two halves match exactly.Do the two halves match?
- Write the answer. Yes
Check. Trace one half, then the other. They are the same shape. ✓
Watch out. A vertical line goes straight up and down. A sideways or slanting line does not count here.