Sides and vertices of 2-D shapes: what children learn
In this game children put sets of shapes in order by their number of sides or vertices, fewest first. To order them, they need to know that a triangle has 3 sides, a square and a rectangle 4, a pentagon 5, a hexagon 6 and an octagon 8.
Supports part of Common Core 2.G.A.1: recognizing shapes by their number of sides and angles. This focused game does not cover the entire standard.
Common Core connection: 2.G.A.1. This is focused practice for part of the standard.
How to play
Put the numbers in order. Use the arrow buttons, or pick one card and then another to swap them. Each game has 5 rounds. After you press Check, the correct order is shown if you got it wrong.
Step by step
- Know the names. Triangle 3 sides, square and rectangle 4, pentagon 5, hexagon 6, octagon 8. The start of the name often helps: pent means 5, hex means 6, oct means 8.
- Sides and vertices match. For these shapes, the number of sides is the same as the number of vertices. A hexagon has 6 sides and 6 vertices.
- Count carefully. When counting, put a finger on one side and mark where you started so you do not count a side twice.
- Order from fewest to most. Find the shape with fewest sides first, then the next, until all are in order.
Worked examples
Example 1: Put hexagon, triangle, square in order by sides, fewest first.
Working: 3, 4, 6.
Answer: triangle, square, hexagon
Example 2: How many vertices does a pentagon have?
Working: A pentagon has 5 sides and 5 vertices.
Answer: 5
Example 3: Put octagon, rectangle, pentagon in order by vertices, fewest first.
Working: 4, 5, 8.
Answer: rectangle, pentagon, octagon
Common mistakes and how to fix them
- Thinking an octagon has 6 sides. Link oct to octopus: an octopus has 8 arms and an octagon has 8 sides.
- Thinking a square is not a rectangle. A rectangle has 4 square corners. A square does too, so a square is a special rectangle.
- Not recognizing a shape that is turned or stretched. Count the sides: any shape with 6 straight sides is a hexagon, even if it looks unusual.
Activities to try at home
- Find shapes on road signs, tiles and windows and count their sides.
- Make shapes with lolly sticks or straws.
- Draw a shape for someone to name by its sides.
Ideas for the classroom
- Use geoboards to make shapes with a given number of sides.
- Sort shapes in a Venn diagram: 4 sides / not 4 sides.
- Describe a hidden shape using its sides and vertices for others to guess.
Free printable game and worksheet
The free printable starts with a game sheet, such as a color-by-answer picture, an answer maze or a secret-code joke, followed by a worksheet. Both use the same checked questions as the online game, and the answers are on the last page. Print it, or save it as a PDF from your browser’s print menu.
Open the free printable game and worksheet
Frequently asked questions
How should I choose this game for my learner?
Supports part of Common Core 2.G.A.1: recognizing shapes by their number of sides and angles. This focused game does not cover the entire standard.
Why do all the shapes have straight sides?
Circles have no straight sides or vertices, so they cannot be ordered in the same way.
Can it be played with a keyboard?
Yes. Tab to a card's up or down arrow button and press Enter or Space to move it, then choose Check.