# Shape Recognizer—More Shapes Sub Trajectory: classifying

Recognizes most familiar shapes and typical examples of other shapes, such as hexagon, rhombus (diamond), and trapezoid.

See the document "2D Shape Descriptions" in the Resources tab, then select "For Teachers."

## Other Examples:

• A child differentiates a typical hexagon as different from a typical rhombus because it has 6 versus 4 sides.
• A child identifies a rhombus and trapezoid as different types of quadrilaterals than a rectangle.

Explorations and discussions involve more than the shapes typically named in our culture, such as typical examples of hexagons (6-sided shapes, often with all sides and angles the same), rhombuses (four equal sides), and trapezoids (1 pair of parallel sides).

Practice-based Research: Most early childhood math programs teach only four familiar shapes (circle, square, triangle, and rectangle) and typically show only standard examples of these shapes,. Research shows, however, that such limited experience restricts children’s development of geometric ideas. [LT]2 engages children with other interesting and important shapes, such as trapezoids and rhombuses as well as richer experiences with familiar shapes.

Children usually refer to rhombus as diamond. Accept that name but mirror "rhombus" back to children. Encourage the mathematical term rhombus because diamond is often misunderstood. Many people think a diamond’s orientation must always be straight up and down. Children are proud to learn and use accurate math language.

All squares are rhombuses—and not just when they are tilted—because a square has four sides of equal length. Squares are also rectangles due to their right angles. However, not all rhombuses are squares because a rhombus does not always have right angles.

Activities like Is It or Not? develop sorting and classifying abilities. Sorting by mathematical properties is perhaps the most important type of classifying activity. Children learn to sort by mathematical attributes in the same way they sort by other attributes, such as color, thus deepening their understanding of mathematical attributes. Children also learn that classifications of such attributes are an important aspect of mathematics.

Alternating ways of making shapes for Don't Burn Your Feed (tape, chalk, cut, or enlarged) on different days helps children generalize their shape knowledge by seeing different representations of the same geometric ideas.