The perimeter of figures with straight sides is defined and illustrated as the distance around the outside of the figure, going from a starting point at one corner, and returning to that corner.
Students learn that to find the perimeter, you add the lengths of all the sides.
The area is defined as the amount of flat space covered by a shape, and is measured in square units.
A square unit is defined as a square in which each side is 1 unit long. The square unit can be used to measure the area of figures. The student learns to estimate area by dragging representations of square units onto a shape and counting the square units.
The definition of area is illustrated as rectangles divided into square units. The result is an array, similar to that used in defining multiplication. Area is defined as the product of the number of squares in the length times the number of squares in the width, length x width = area.