This applet allows students to investigate the optimal area and optimal perimeter of a rectangle.
Drag the vertices Width and Length to change the dimensions of the rectangle.

What is the optimal area of a rectangle?
Find as many pairs of dimensions as you can that give a perimeter of 20cm. Which of these pairs gives the optimal area?
What is the optimal perimeter of a rectangle?
Find as many pairs of dimensions as you can that give an area of 36cm. Which of these pairs gives the optimal perimeter?