Subitizing is the ability to ‘see’ a small amount of objects and know how many there are without counting. Subitizing is what tells you what number you roll on a six sided dice – most adults no longer have to count the pips after playing board games for a while. Subitizing is a fundamental skill in the development of students’ understanding of number (Baroody 1987, 115). Students use patterns recognized to discover properties and skills such as conservation, compensation, unitizing, counting on, composing and decomposing numbers, as well as understanding of arithmetic and place value. The ability to subitize can be developed, and uses a student’s pattern recognition skills. Part part whole understanding is usually used to subitize numbers over four or five. This means a student looking at this pattern doesn’t usually see 7, but instead 1 and 6, or maybe 2 and 5. This is one of the reasons larger patterns shouldn’t be used until students are familiar with various representations of numbers 1 to 5. When two colours are used in patterns, they also draw attention to smaller anchors and make the parts more obvious. Here is an article that speaks about the why and what of subitizing. These websites have many downloads for educators to use in whole and small group work (Try this one out too!). Teaching Math has many resources for this. Here are Dot Cards and another set of Dot Cards that are large enough for class discussion. Here is another teacher resource that thinks about dot cards and ten frames as a tool for subitizing. Pinterest also has a great tag for subitizing ideas.