# Circles

A variety of circle related activities.

### Circles

These 15 instant maths ideas, ideal for use as starter questions, extension question or probing questions to assess understanding, require students to perform a practical experiment in order to estimate a value for pi, describe a circle over the phone, find a connection between the length of the radius of a circle and the area of the circle, explore different series giving approximations for pi, investigate problems requiring the calculation of circumference and calculate the number of revolutions per minute of a spinning object.

### Circle Measurement

This SMILE resource contains two packs of games, investigations, worksheets and practical activities.

Circle measurement pack one contains nine work cards with a wide variety of activities covering finding the length of a running track and the circumference of a circle, naming different parts of a circle, and calculating the area of a circle.

Circle measurement pack two contains ten work cards with activities requiring students to investigate packing circles into a square, find the area of a sector of a circle, find approximations to pi, and find the area of non-uniform shapes.

### Square and Circle Inquiry

This Inquiry Maths problem states "a square fits into a circle better than a circle fits into a square" leading to a rich task exploring areas, ratios and percentages.

### Circles and Cylinders

Circles and Cylinders covers, an introduction to circles, naming the different parts of a circle, estimating the circumference of a circle, eatimating the area of a circle, formulae for circumference and area, problems in context and the volume and surface area of a cylinder.

### Circles rolling on circles

An article from +plus magazine exploring the number of revolutions made when one coins rolls around another with a surprising result.

### Circles with Whole Number Points

Circles with Whole Number Points provides teacher inspiration for investigating equations of a circle and Pythagoras’ theorem. The student task sheet refers to the use of Geogebra. The task consists of drawing circle, centre (0,0), radius 5 and finding all the points with integer coordinates through which the circle passes. The activity can be extended by altering the radius of the circle or moving the centre of the circle from the origin

### Circle Geometry

Three advanced level lesson ideas designed to explore the properties of circles and their equations. Each activity is accompanied by teacher notes suggesting how the activity could be delivered and possible extension ideas.