Here is a small rectangle on the board, and beside it a bigger copy of exactly the same shape.

What got bigger? And by how much? Roughly how many times taller and wider is the second one?

Watch these shapes on the grid, each with its enlargement drawn beside it. Look at the sides of each copy compared to the original.

A side of 3 squares becomes 6 when we multiply by 2 — not 5, as if we added 2. That multiplier is the scale factor: the number we multiply every side by.

The copy keeps its proportions. That means it stays the same shape: the angles do not change and every side grows together, so it is never squashed or stretched.

Before the last jump, we flip the skill and find a scale factor from two lengths. An original side measures 2 squares and the matching side on the image measures 8 squares. Divide image length by original length: 8 ÷ 2 = 4. The scale factor is 4. Check a second pair of sides the same way so every length agrees.

Then finish with the final challenge: enlarge the triangle by scale factor 4 to match the copy that is four times the size.