What happens to the perimeter of triangle ABC as the two smaller
circles change size and roll around inside the bigger circle?
Draw a 'doodle' - a closed intersecting curve drawn without taking pencil from paper. What can you prove about the intersections?
I want some cubes painted with three blue faces and three red faces. How many different cubes can be painted like that?
This proved quite a challenge! It was Helen
(Maidstone Girls' Grammar) and Joel (of ACS in Singapore) who
correctly found that only 3 weighings are needed.
Here is one way to solve the problem. We've
labelled the coins ABCDEFGHIJKL.
At West Flegg Middle School Polly and Rebecca
found a method for 4 weighings, as did Michael (Cranmore Primary
School, in Perth, West Australia).