If it is broken, how can you fix it? Garry Clark describes the use of some simple software as a device to challenge children's calculation strategies

Calculators can be used in primary schools in a number of situations. They are most beneficial when working with large numbers, dealing with real data that leads to complex calculations, performing repetitive calculations, developing concepts, estimating and checking, problem solving and looking for patterns and/or relationships. But what if the calculator is broken? This article describes the mathematics that children learnt and a teacher's awareness of children's mathematical understanding, when a "broken calculator" activity was undertaken regularly over two terms.