To express the side length of a square in terms of its perimeter $P$, you can use the following steps:

1. The formula for the perimeter $P$ of a square is given by: $P = 4s$ where $s$ is the side length of the square.

2. To find the side length $s$, solve for $s$ by dividing both sides of the equation by 4: $s = \frac{P}{4}$

So, the expression for the side length $s$ of the square in terms of its perimeter $P$ is:

$s = \frac{P}{4}$

Would you like more details or have any questions? Here are five related questions you might find interesting:

1. How do you express the area of a square in terms of its perimeter?
2. If the perimeter of a square is doubled, how does the side length change?
3. What is the relationship between the side length and the diagonal of a square?
4. How does the area of a square change if its side length is halved?
5. How can you express the side length of a square in terms of its area?

Tip: When solving for a variable, isolate it by performing inverse operations on both sides of the equation.