A good way to introduce your students to the concept of perimeter is to let them loose in the classroom with rulers and tape measures. Explain that a perimeter refers to the measurement of the edges of an object. Distribute rulers and tape measures and give them a set amount of time to find any objects they can and measure their perimeter. Some students will focus on small objects, while others might try measuring the perimeter of the entire room. Ideally, the activity will allow them to figure out for themselves how perimeter works.
Worksheets provide a quiet and solitary way to teach students to calculate perimeter. Make a worksheet containing a variety of different shapes and the measurements of their sides. Have students work alone to calculate the perimeter of each shape. When students are done, take up their work and ask the class if anyone has figured out a formula for calculating the perimeter of any of the shapes. A student might, for example, have figured out that the perimeter of a square is equal to one of its sides multiplied by four.
Make a lesson on perimeters more interesting by using narrative. Come up with one or more scenarios that help teach perimeter. For example, write a short paragraph about a person searching for his lost cat. He might walk around the outside of his house, before walking along two sides of his fence. Give the dimensions of the walls and the fence. Have students figure out far the man has traveled.
Students sometimes have trouble with mathematical concepts because they don't see their practical applications. Have your class come up with a list of situations in which you would need to calculate a perimeter. Students might suggest knowing how much paint to buy for a house or calculating the time it takes to walk your dog. When you have enough ideas, assign one to each student as a homework project. Students must calculate the perimeter of whatever they have been assigned, be it the outside of their house, the distance around the block or the perimeter of their kitchen table.