TOPIC 4 · GRADE 3 FOUNDATION

The Quadrilateral Family

Sort four-sided shapes by parallel sides, equal sides, and right angles.

MA.3.GR.1.2

BIG IDEA

Shape categories can overlap. A square is also a rectangle, a rhombus, a parallelogram, and a quadrilateral because it satisfies every definition.

WHAT TO KNOW

A quadrilateral is any polygon with exactly four sides.
Parallelograms have two pairs of parallel sides; rectangles add four right angles; rhombi add four equal sides.
A square has four equal sides and four right angles, so it belongs to several nested families.

WATCH OUT

Calling a square a rectangle is not a mistake. A rectangle is defined by four right angles, not by having unequal side lengths.

TRY IT

Select a shape to reveal its attributes and all the families it belongs to.

Choose the next topic from the lesson rail when you are ready.