A spherical balloon lies inside a wire frame. How much do you need
to deflate it to remove it from the frame if it remains a sphere?
Four Points on a Cube
Age 16 to 18 Challenge Level:
Take a cube of side length one unit. A vertex of the cube and
the centres of the three faces not containing that vertex form the
vertices of a tetrahedron. What is the surface area of this
The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the
NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to
embed rich mathematical tasks into everyday classroom practice.