Maze consists of squares containing identities, some of which are false. Pupils can only pass through squares containing true identities. Identities require ability to expand & factorise quadratic expressions and simplify algebraic fractions, so really only good for a GCSE top set. Extension - pupils find identities of incorrect squares and then design their own maze (there's a good discussion to be had about how to make a good maze - including common misconceptions to fool people).