Perimeter

A complete lesson on perimeter, with a strong problem solving element. Incorporate a set of on-trend-minimally-different questions and several opportunities for pupils to generate their own questions. Also incorporates area elements, to deliberately challenge the misconception of confusing the two properties of area and perimeter.

Activities included:

Starter:
A few basic perimeter questions, to check pupils know what perimeter is.

Main:

• Pupils come up with a variety of shapes with the same perimeter, then discuss answers with partners. Designed to get pupils thinking about which answers could be different, and which must be the same.
• A slight variation for the next activity - pupils are given diagrams of pentominoes (ie same area) and work out their perimeters. Raises some interesting questions about when perimeter varies, and when it doesn’t.
• A third activity based on diagrams a bit like the cover image. Using shapes made from different arrangements of identical rectangles, pupils work out the perimeters of increasingly elaborate shapes, some of which can’t be done. Questions have been designed so that only slight alterations have been made from one diagram to the next, but the resulting perimeter calculations are varied, interesting and sometimes surprising (IMO!). Has the potential to be extended by pupils creating their own shapes and trying to work out when it is possible to calculate the perimeter.

Plenary:
A closer look at the impossible questions, using a couple of different methods.

Printable worksheets and answers included, where appropriate.

Please review if you buy as any feedback is appreciated!