Working systematically

How have "Warmsnug" arrived at the prices shown on their windows? Which window has been given an incorrect price?

Investigate the smallest number of moves it takes to turn these mats upside-down if you can only turn exactly three at a time.

How many different ways can you find to join three equilateral triangles together? Can you convince us that you have found them all?

A 2 by 3 rectangle contains 8 squares and a 3 by 4 rectangle contains 20 squares. What size rectangle(s) contain(s) exactly 100 squares? Can you find them all?

A Sudoku with clues as ratios.

A Sudoku with a twist.

Can you hang weights in the right place to make the the number balance balanced?

How many trains can you make which are the same length as Matt's and Katie's, using rods that are identical?

If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?

The teacher has forgotten which pupil won which medal. In how many different ways could he give the medals out to the pupils?