Perimeter investigation

A complete lesson or maybe two, where pupils consider how perimeter varies for rectilinear shapes. Sounds simple but it involves pupils investigating and using algebra to form and solve equations. Designed to follow on from another lesson I’ve put on the TES website about perimeter, although it works as a stand alone lesson too.

Activities included:

Starter:
A quick task to get pupils thinking about when perimeter varies and when it doesn’t.

Main:

• Three similar-but-different scenarios for pupils to investigate, by drawing different shapes that fulfil given criteria, before trying to spot patterns and generalise about perimeter. One of these scenarios is a ‘non-example’, in that the exact perimeter cannot be found. These scenarios are each formalised using some basic algebra, to model how to approach the next task.
  I’ve also attached a Geometer’s Sketchpad file which has these questions shown dynamically. If you don’t have GSP, no problem, as I have endeavoured to show the same information within the powerpoint.
• A set of related perimeter questions, requiring pupils to form simple equations to answer. Includes a few more non-examples, to help deepen pupils’ understanding of the algebra involved.

Plenary:
A prompt for pupils to reflect on the subtly different ways algebra has been used within the lesson.

Printable worksheets and answers included.

Please review if you buy as any feedback is appreciated!