L24 – WWW – Decompose Shapes

Working Without Worksheets – Reception Maths: Decomposing Shapes Help your Reception pupils build spatial reasoning with this Working Without Worksheets lesson on decomposing shapes. Building on the previous lesson about composing shapes, children now explore how larger shapes can be split into smaller ones. Using tangrams, playdough, and shape cutters, they learn that a single shape can be divided in different ways while keeping its properties. The lesson begins with a starter activity: Show a square and ask: “Can you see any smaller shapes inside the square?” Model cutting the square into 2 rectangles, then into 2 triangles. Emphasise that the square is still made up of shapes that have their own properties. In the main input, children explore tangrams: Show a square tangram and explain that the large square has been split into many smaller shapes. Ask: “What shapes can you see in the square?” Examine the shapes in turn. Point out that there are 5 triangles —all have 3 sides, but they appear in different orientations and sizes. Discuss how decomposing a shape helps us see both parts and wholes. For the independent activity, children explore decomposition hands-on: Playdough Decomposition – children cut out a square, rectangle, or triangle from playdough. They then use a tool to cut the shape into 2, 3, or 4 smaller shapes. Encourage them to describe what they made: “I cut a square into 2 triangles” or “I cut a rectangle into 3 smaller rectangles.” Discuss whether the new shapes are the same or different. The plenary consolidates learning: Bring the class together to look at examples of decomposed shapes. Reinforce that a whole shape can be split into parts in many ways. Link back to composing shapes: shapes can join together and also split apart. What’s Included in the Pack? ✔ Full teacher planning with objectives, vocabulary, and plenary questions ✔ Starter: explore smaller shapes inside a square by cutting it into parts ✔ Teacher modelling: use a tangram to