So what is subitising? It is the ability to instantly recognise the number of objects in a small group without needing to count them (follow this link for more background info on subitising). Most adults can recognise quantities of up to 5 and for larger quantities, we usually see different groups and automatically add them together. I recently learned that children develop the ability to subitise the numbers 1 or 2 before they learn to count with 1-1 correspondence. Practising counting with quantities that children can already subitise actually undermines their confidence in their own understanding of number.
Subitising is an important skill for children to master and helps them to build their understanding of number. One website I often use is the Doorway Online Up to 10 activity. It is very versatile because you can select whether you want the objects to appear in a tens frame or randomly. You can also specify which numbers to 10 you want to work with and avoid those that are too large or small.
The good news is that children can learn to subitise by hearing other people’s strategies. In the example above, children might say they saw a group of 5 then 1 more, or groups of 2, 3 and 1. Talking about numbers is this way also helps children explore skills such as partitioning and develops their understanding of how numbers can be combined or split in different ways.