Calculate the perimeter of different shapes

Open the area/perimeter interactive. Begin by setting the area of the shapes to 6 square units and check the box for only rectangular shapes.

In a spreadsheet program or note-taking tool, set up a table with four columns, labelled 'Height', 'Width', 'Area' and 'Perimeter'. Now click on the "Draw New Shape" button in the interactive, and calculate the distance around the outside of the shape (the perimeter). You can check your answer. Each time you generate a new shape, fill in each piece of information. Do you see a pattern?

• How many different shapes do you get? What if you change the area of the shapes?
• Is there a quicker way to find the perimeter than counting around the outside of the shape?