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Learn what makes a shape a shape — and what doesn't matter at all!
People have been looking at shapes for a very, very long time! Long ago, people noticed that things in the world have different forms. A rock might be round. A door might have four sides. A slice of pizza looks like a triangle. People wanted to give these forms names and learn about them.
Here is the big question we will answer today: What makes a shape that shape? Is a triangle still a triangle if it is blue? What if it is really tiny? Let's find out!
Every shape has things about it that we can describe. We call these things attributes. An attribute is just something you can say about a shape. Some attributes are super important. Others don't matter at all!
Let's look at a picture that shows defining attributes and non-defining attributes side by side. This will help you see what matters and what doesn't!
In the picture, you can see four triangles. One is purple and big. One is blue and small. One is pink and tilted to the side. One is yellow and tall. They all look different! But guess what? They all have 3 sides and they are all closed. So they are ALL triangles!
Each shape has its own set of rules. These rules tell you exactly what makes that shape special. Let's learn the rules for some shapes you know!
Let's practice sorting attributes into two groups. Look at the chart below. On one side, you see things that DO matter (defining). On the other side, you see things that DO NOT matter (non-defining).
Look at the green side. Those are the things you must check when you name a shape. How many sides? Are they straight? Is it closed? Now look at the pink side. You can change any of those things and the shape keeps its name. A big red triangle and a tiny green triangle are both triangles!
Imagine your teacher shows you a big, blue, tilted shape. How do you figure out what shape it is? Let's go step by step!
Let's compare some shapes! This table shows you the defining attributes of different shapes. See how each one follows its own set of rules.
| Shape | Number of Sides | Closed? | Special Rule |
|---|---|---|---|
| 🔺 Triangle | 3 | Yes | 3 corners |
| ⬜ Rectangle | 4 | Yes | 4 square corners (a square is a special rectangle with 4 equal sides) |
| ⬟ Hexagon | 6 | Yes | 6 corners |
| ⭕ Circle | 0 straight | Yes | Perfectly round, no corners |
Now that you know the rules, you can build and draw shapes yourself! When you draw a shape, you use its defining attributes as your guide. Let's practice drawing a triangle and a rectangle step by step.
| What You Know Now | What You'll Learn Next |
|---|---|
| Name shapes by their defining attributes | Sort shapes into different groups |
| Tell which attributes don't matter | Cut shapes into halves and fourths |
| Draw shapes with the right number of sides | Build 3D shapes (cubes, cones) |
In second grade, you'll learn about 3D shapes like cubes and spheres. You'll also learn to split shapes into equal parts. The rules you learned today will help you with all of that! You're already becoming a shape expert.
Now it's your turn! Try these five questions. Think about what makes a shape that shape. Remember to focus on the defining attributes!
Today you learned about attributes of shapes. Every shape has defining attributes — the rules it must follow, like the number of sides, being closed, and the number of corners. Shapes also have non-defining attributes like color, size, and orientation — these can change and the shape keeps its name.
A triangle always has 3 sides and is closed. A rectangle always has 4 sides and 4 square corners — and a square is a special rectangle where all 4 sides are the same length. A circle is always perfectly round with no corners. Now you can look at any shape, check its defining attributes, and name it — and you can build and draw shapes by following the right rules. Great job, shape detective!