Decompose shapes into smaller shapes

A two-dimensional shape can be partitioned into smaller familiar shapes, such as triangles, squares, rectangles, and circles, while the pieces together cover the original shape without gaps or overlaps. The learner identifies and describes different valid decompositions and understands that a shape’s appearance may change when divided, supporting later work with composing shapes, area, and geometric properties; formal area calculations and generalized decompositions are not included.

Detailed Explanation: Decompose shapes into smaller shapes

Look at the whole shape first. Ask yourself: What smaller shapes do I recognize?

Example

Imagine a shape that looks like a house:

The bottom part is a rectangle.
The top part is a triangle.

To decompose the shape:

Find where the triangle roof meets the rectangle.
Draw a straight line across that place.
Now the large shape is split into two smaller shapes:
- one rectangle
- one triangle
Check the pieces. They fit together to make the whole house shape.
Make sure there are no gaps between the pieces and that the pieces do not overlap.

So, the house shape can be decomposed into a rectangle and a triangle.

Learn by doing: Decompose shapes into smaller shapes

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Shape Composites - Composite Shape Picture to Shape Set

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