Test yourself:
Choose the set of cards to be used and hold them numbers side up, shuffled. Select the top card. As you decide on your answer, place your card in one of three rows- top row were correct; middle row took a long time to work out; bottom row were wrong. Now you know which ones to concentrate on.

Let someone else test you, with others maybe as well – keep a written record of how you perform. In class this is often how it works, round a table with students of similar ability.

Place a selection of the cards, numbers side up, in any order in an array. Take it in turns to select one according to verbal instructions, for example:

• Take the two cards where the answer is the same but the colours are different.
• Take a card where the answer lies between 33 and 36.
• Take a card where the answer is bigger than 62 but smaller than 65.
• Take a card showing a an answer in the forties.
• Take the cards showing pixie.