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Shapes: Glossary

teacher and child playing with geometric shapes
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Here are some key terms to remember when teaching your child about shapes.
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You can learn more about how to playfully teach your child about shapes at home in the Parent Workshop: Shapes.

Terms for Parents

  • Geometry is the type of mathematics that deals with shapes and their properties.
  • Shapes are geometric figures. They are two-dimensional when they lack depth (flat shapes). For example, a square is a two-dimensional shape. Shapes are three-dimensional when they have length, width and depth (solid shapes). For example, a cube is a three-dimensional shape.
  • Congruent shapes are those that have the same shape and size as each other.
  • Composed shapes are shapes that are made of two or more shapes.
  • Decomposing shapes refers to when we break down composed shapes into smaller ones.
  • Symmetrical shapes are those that, when split down the middle, are the same in size and shape on both sides of the line. For example, an equilateral triangle is symmetrical because if you draw a line right down its center, the two shapes on each side of the line are exactly the same.
  • A shape has open sides and angles when one side of the shape does not touch the others.
  • A shape has closed sides and angles when all its sides connect to each other. For example, a square has closed sides and angles.

Math Talk

The more you talk with your child about shapes, the more your child's ability to recognize shapes will grow. Here are some conversation starters to practice with your child:

  • "I can fold these shirts into squares. A square has four equal sides."
  • "The hole for the top of this shirt is round like a circle or an oval. It has no corners."
  • "These bowls have circles on top and the bottom. They are perfectly round."
  • "What shapes are these dishes? How do you know?"
  • "How is that shape like this one? How is it different?"
  • "Our kitchen drawers are giant rectangles with four sides and four corners."
  • "Can you make a triangle with popsicle sticks?"
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Related Workshop

This article is part of our Shapes workshop, which helps parents and caregivers playfully build children's ability to recognize shapes.