Subitizing is the ability to instantly recognize the number of objects in a small group without counting them individually. It is a foundational early math skill that enables children to understand number cardinality, develop number sense, and transition from counting to rapid grouping. Typically, people can instantly subitize sets of four or fewer.
Children learn to subitize – from observation and experience – without specifically being taught to 'how to do it'. Certainly there is no need use the word: it will probably come-up in parent-teacher meetings. The idea of enriching 'home-life' is to provide opportunities. We have designed ten 'subitizing cards' as part of the Usk set. (We would love to make dozens more – when funds permit.)
Since the Usk Set of cards is designed to cover all the digits there is a full set of ten subitizing digit-cards. (There is a blank for zero, which is a digit, but not a counting number.) We do not suggest that you use the random-dots card for emphasis on subitizing: that will come when they are used in matching activities.
Ideally you will be nudging subitizing techniques with counting practice. As a youngster I remember cashiers counting coins in pairs as they slid two pennies of a table under their first two fingers: "two-four-six-eight-ten-one shilling". Subitizing twos is fairly easy.
Counting in threes is less common, but being able to 'see three-in-a-group' is useful. Our belief in that prompted the design of the ten cards in the Usk Set which are dots in an ordered fasion on a nine-grid (or nine-frame). This 'noughts and crosses' grid also shows three groups of three. Subitizing random 'nines' is not possible: but spotting three groups of three is powerful. (Small cubes lend themselves to this, also.)