Definition:
The total distance around the outside of a
square

Try this
Drag any orange dot to resize the square. The perimeter is calculated as you drag.

How to find the perimeter of a square

Like any polygon, the perimeter is the total distance around the outside,
which can be found by adding together the length of each side.
I the case of a square, all four sides are the same length,
so the perimeter is four times the length of a side. Or as a formula:

In the figure above, drag any orange dot to resize the square. From the side length shown, calculate the perimeter
and verify your result matches the formula at the top of the diagram.