Rule: add 2 triangles each step
A shape pattern is a row of shapes that grows by a rule. Today we'll use the rule to figure out what comes next.
Here's our rule: each step adds two more triangles than the step before.
Step one starts with just this one triangle.
Step two has three triangles — that's two more than step one.
Step three has five triangles — two more again. The rule is working!
So what should step four look like? Let's use the rule.
Step three had five, so we add two more. One… two.
Now let's count the triangles in step four: one, two, three, four, five, six, seven.
Step four has seven triangles. When you know the rule, you can keep the pattern going forever!
Now you try. Count the corners of this shape. How many corners?