**TES Maths Resource of the Week**

**Resource title: **ISS Earth circumference

**Resource author:** grahamcolman

**What is it?**

As I wrote about in this blog piece, I am not a fan of shoe-horning real life scenarios into maths topics when they simply do not belong. However, here is an example that is definitely worthwhile.

Given only a limited set of information, students must use their knowledge of circles to estimate the circumference of the earth. Solving this question requires use of the speed-distance-time formula, calculating a radius and a circumference, plus converting between different units of measure – exactly the same multi-skill questions that will dominate the new GCSE.

There is a full solution provided, together with suggested extensions and adaptations.

**How can it be used?**

This activity would work well either at the end of a series of lessons on area and circumference of circles, or perhaps better still as a way of introducing the topic to students who have met it before, but not for a long time. I could imagine something like this giving my Year 11 class a much-needed jolt!

The task may appear too unstructured for some students, so it is a good idea to have a few prompts on standby, such as “can you draw a diagram to help?” or “how might we go about calculating the radius?”.

Less structured questions like this, covering several different topics, will be far more common in the new GCSE. So, it is important that students are exposed to them as soon as possible, and allowed to try – and quite possibly fail – in order to build up their levels of confidence.

Craig Barton

*Craig is a secondary maths teacher in the North of England.*