Draw two possible rectangles for each perimeter of 8 units

The perimeter of a rectangle is the sum of all its sides, so its 2 lengths + its 2 widths, or 2l + 2w.

So you need 2l + 2w to equal 8.

2l + 2w = 8.

You can divide both sides by 2.

l + w = 4.

So now it comes down to two positive numbers that add up to 4. You can have 3 and 1, 2 and 2, 1.5 and 2.5, etc.