Two circles of equal size intersect and the centre of each circle is on the circumference of the other. What is the area of the intersection? Now imagine that the diagram represents two spheres of. . . .

Practice your skills of measurement and estimation using this interactive measurement tool based around fascinating images from biology.

Scientist Bryan Rickett has a vision of the future - and it is one in which self-parking cars prowl the tarmac plains, hunting down suitable parking spots and manoeuvring elegantly into them.

Can you choose your units so that a cube has the same numerical value for it volume, surface area and total edge length?

Making a scale model of the solar system

Design and test a paper helicopter. What is the best design?

A white cross is placed symmetrically in a red disc with the central square of side length sqrt 2 and the arms of the cross of length 1 unit. What is the area of the disc still showing?

From the measurements and the clue given find the area of the square that is not covered by the triangle and the circle.