What+number+am+I+thinking+of?

What number am I thinking of? Key idea: Complete simple number sentences by calculating the value of a missing number Materials: Cards with number sentences, with one number in each covered by a flap (see below) Make cards with number sentences on them and cover one number on each card with a flap. Later, pose problems such as those above and support students to write number sentences and calculate the missing number. Students should also pose similar problems.