2D and 3D Shapes: Explained For Primary Parents and Kids!
A 2D shape is a shape with two dimensions, such as width and height; a 3D shape is a shape with three dimensions, such as width, height and depth.
2D and 3D Shapes: What’s the Difference?
A 2D shape cannot be physically held, because it has no depth; it is completely flat. The thin plastic shapes that are sometimes used to represent 2D shapes are actually 3D because they do have depth to them – even if it’s very small.
It is hard to give an example of a truly two-dimensional shape – perhaps a shadow, or a reflection. However, in the primary curriculum, children only need to know the names and understand the properties of the most common 2D shapes, which are shown below.
3D shapes can be picked up, held and moved around. Nearly everything we see and interact with in our day to day lives is a 3D object, from Lego bricks to sunflowers.
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Which 2D Shapes will my child learn about?
In primary school, your child will learn about the following polygons, regular and irregular shapes.
(A polygon is a 2D shape with straight sides. A regular shape has all sides the same length and all interior angles the same size. An irregular shape has different length sides and/or interior angles.)
Which 3D Shapes will my child learn about?
In the primary curriculum, children must know the names and properties of the 3D shapes below (although, as with the 2D shapes in the grid above, these will be introduced at different ages).
(Faces are the flat sides of the 3D shapes; edges are where two faces meet; vertices are where three or more edges meet.)
When will my child learn about 2D and 3D shapes in primary school?
Geometry is taught in every year group in KS1 and KS2. Here’s what the National Curriculum expects to be taught about 2D and 3D shapes, separated by year:
Year 1 pupils should be able to:
- Recognise and name common 2-D and 3-D shapes, including: 2-D shapes [for example, rectangles (including squares), circles and triangles]; 3-D shapes [for example, cuboids (including cubes), pyramids and spheres].
- Non-statutory guidance: Pupils handle common 2-D and 3-D shapes, naming these and related everyday objects fluently. They recognise these shapes in different orientations and sizes, and know that rectangles, triangles, cuboids and pyramids are not always similar to each other.
Year 2 pupils should be able to:
- 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, [for example, a circle on a cylinder and a triangle on a pyramid]
- Compare and sort common 2-D and 3-D shapes and everyday objects.
- Non-statutory guidance: Pupils handle and name a wide variety of common 2-D and 3-D shapes including: quadrilaterals and polygons, and cuboids, prisms and cones, and identify the properties of each shape (for example, number of sides, number of faces). Pupils identify, compare and sort shapes on the basis of their properties and use vocabulary precisely, such as sides, edges, vertices and faces.
Year 3 pupils should be able to:
- Draw 2-D shapes and make 3-D shapes using modelling materials and recognise 3-D shapes in different orientations and describe them.
- Non-statutory guidance: Pupils’ knowledge of the properties of shapes is extended at this stage to symmetrical and non-symmetrical polygons and polyhedra. Pupils extend their use of the properties of shapes. They should be able to describe the properties of 2-D and 3-D shapes using accurate language, including lengths of lines and acute and obtuse for angles greater or lesser than a right angle.
Year 4 pupils should be able to:
- Identify lines of symmetry in 2-D shapes presented in different orientations.
- Non-statutory guidance: Pupils continue to classify shapes using geometrical properties, extending to classifying different triangles (for example, isosceles, equilateral, scalene) and quadrilaterals (for example, parallelogram, rhombus, trapezium).
Year 5 pupils should be able to:
- Identify 3-D shapes, including cubes and other cuboids, from 2-D representations and distinguish between regular and irregular polygons based on reasoning about equal sides and angles.
Year 6 pupils should be able to:
- Draw 2-D shapes using given dimensions and angles and recognise, describe and build simple 3-D shapes, including making nets.
How do 2D and 3D shapes relate to other areas of maths?
When working with fractions, children will often have to shade a fraction of a shape. They will have to relate their understanding perimeter and area to 2D shapes and volume to 3D shapes. They may be required to reflect or translate 2D shapes on a coordinate grid.
Wondering about how to explain other key maths vocabulary to your children? Check out our Primary Maths Dictionary, or try these other terms related to 2D and 3D shapes:
1. Which of these shapes is a pentagon?
(Answer: bottom left)
2. Which shape has exactly 5 faces?
3. These two shaded triangles are each inside a regular hexagon. In each hexagon, is the triangle an equilateral, isosceles or scalene?
(Answer: 1st: isosceles 2nd: scalene)
4. Here is a drawing of a 3D shape.
Complete the table.
(Answer: Faces: 6 Vertices: 8 Edges: 12)
5. Is this rhombus a regular quadrilateral? Explain how you know.
(Answer: No – not all angles are the same)
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