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Understand Shape Hierarchies and Subcategories

Students will learn that shapes in different categories can share attributes that define a larger category. For example, rhombuses, rectangles, and squares are all quadrilaterals because they all have 4 sides. They will explain why a square is also a rectangle and a rhombus.

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Understand Shape Hierarchies and Subcategories

Grade 3 · Shape Attributes and Categories · question 1 of 3

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12 rungs. A star at the top.

HJKL

Quadrilateral HJKL — choose its most exact name.

Choose its name.

How it is taught

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A rhombus has four equal sides.

It is a kind of quadrilateral.

A shape can belong to more than one family.

1234

Read it: Rectangles by their corners

5 shapes sit on the table. Which of them are rectangles? Read the marks, not the look.

  1. A rectangle has 4 square corners.
  2. Find the shapes with a square mark in every corner.
  3. The rectangle and the square: 2 rectangles.

The marks on a shape tell what is true about its sides and corners.

A square has 4 square corners, so it is a rectangle too.

A parallelogram has 2 pairs of parallel sides, so it is a trapezoid too.

Name a shape by its marks. 1 shape can have 2 names.

Leaving out the square, because it is not long like a rectangle.

Check its corners: 4 square corners. The square is a rectangle too.

A square, a rhombus, a rectangle and a trapezoid with only 1 pair of parallel sides. How many are parallelograms? — 3. The square, the rhombus and the rectangle have 2 pairs of parallel sides. The trapezoid has 1.

A square is a rectangle AND a rhombus

Have you ever wondered why a square is so special? Today we'll see it actually belongs to three shape families at once!

Here's our square. Four straight sides and four corners.

Grade 3 · One shape, three families

First family — a quadrilateral is any shape with four sides.

Let's count: one, two, three, four sides. Yes — our square is a quadrilateral!

Next family — a rectangle is a shape with four right angles, corners shaped like a perfect L.

Look at our square's corners. All four are right angles. So our square is also a rectangle!

Last family — a rhombus is a shape with four sides that are all the same length.

Our square's sides are all equal. So it's a rhombus too!

Amazing — our square is a quadrilateral, a rectangle, AND a rhombus. One shape, three families!

What you see

While they climb, your page writes one true line to ask about tonight, and a short note each Sunday.

MayaGrade 3 · Mathematics
Did you know?

A chessboard has 64 squares — share them out between the 8 rows and each row holds exactly 8.

Today’s goal
1 star — one skill mastered, every rung of its ladder climbed
Climbing now
Divide within 100

An example student.

MayaGrade 3 · Mathematics

Maya earned 2 stars this week — Interpret multiplication as equal groups, which took 6 answers over 3 days before its star landed 3 days ago and Multiply by 6, 7, 8 and 9. Next up: Divide within 100.

An example week.

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