In fact, the word concentration is also worth a moment’s thought. It’s what we want children to do – we say, “For heaven’s sake, Laura, concentrate!”. We regret their ever-shortening concentration span. Concentrating is a good thing.
But in usage, concentration is virtually (though not actually) two words. It has an alternative meaning, applied to soup or fruit juice. A concentration (or concentrate) is a reduction to the essence. It may be helpful to reconnect these two uses of the same word. If we want to support pupils’ concentration, perhaps we need to help them with that reduction, to encourage focus on the magazine cover rather than the whole magazine, on a key aspect, on the tree rather than the whole landscape. Focusing device are selections that we make which concentrate the mind of our pupils.