Using Pattern Blocks to Create Composite Shapes

A composite shape is a new shape made by joining two or more shapes together along their sides. Once several blocks are placed edge to edge, the outline they form together becomes a single new shape, even though it is still made up of the smaller pieces underneath. This is the same idea explored in composing 2D shapes, and pattern blocks are one of the easiest tools for practicing it because their edges are already the same length.

One of the most useful things about pattern blocks is that the same composite shape can often be built from more than one combination of pieces. For example, a hexagon can be created using two trapezoids, six triangles, or three rhombi. This helps show that a shape's identity depends on its overall outline, not on how many pieces were used to make it.

When filling in an outline with pattern blocks, working through the same steps each time helps avoid gaps or overlaps.

1. Look at the overall outline and estimate how large the finished shape should be.
2. Start with the largest blocks, such as the hexagon or trapezoid, to cover as much area as possible.
3. Fill any remaining spaces with smaller blocks like triangles or the thin rhombus.
4. Check the finished outline for gaps or overlapping edges, and adjust the pieces if needed.

This same largest-piece-first approach works whether the outline is a simple shape like a hexagon or a more irregular picture built from several different blocks.

Practicing with pattern blocks builds a strong sense of how shapes relate to one another, which supports later skills like sorting 2D shapes by a single attribute and comparing shape properties. The same reasoning about combining smaller pieces into a larger whole also carries over into three dimensions, as seen in composing 3D shapes.

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