There are 3 NRICH Mathematical resources connected to Proof Sorting, you may find related items under Thinking Mathematically.
Broad Topics > Thinking Mathematically > Proof Sorting
Iff
Age 14 to 18
Challenge Level
Take a triangular number, multiply it by 8 and add 1. What is special about your answer? Can you prove it?
Kite in a Square
Age 14 to 16
Challenge Level
Can you make sense of the three methods to work out the area of the kite in the square?
Proximity
Age 14 to 16
Challenge Level
We are given a regular icosahedron having three red vertices. Show that it has a vertex that has at least two red neighbours.
