Curriculum placement
Grade 5. This describes the skill, not a learner estimate.
Categories and subcategories of shapes
Organize shapes into categories and subcategories
Problem types
- Every name for a shape
- Shape categories
- Properties pass down
- Choose every true shape statement
- Scalene, isosceles or equilateral
Builds on
- Classifying quadrilaterals
- Sides, angles, and faces · Earlier idea
Counting the sides of a polygon to name it grows into sorting triangles by how many of their sides are equal, the first step toward categories that sit inside one another.
Leads to
- Precise definitions in geometry · Extend the idea
A shape belongs to a class when it meets the definition, so a square is a rectangle because it has all the required properties.
- Proofs about parallelograms · See it applied
If every rectangle is a parallelogram, it inherits the properties of parallelograms. Proofs use this to transfer facts between classes.
Related skills
- Parallel lines, perpendicular lines, and symmetry · Related idea
The number of lines of symmetry separates shapes in the hierarchy: a square has four and a rectangle has two.
- Positive and negative numbers · Related idea
Nested classes of shapes work like nested sets of numbers: every integer is a rational number, as every square is a rectangle.
Open the interactive map to explore lessons and skill connections.