Mental models. It is important that students both count discrete objects (sets) and count along continuous lines (number lines). The number line model can be experienced by counting steps and using a number track, and with games like Snakes and Ladders and Ludo and any other board games where they have to count along lines, or games where they have to take the number of strides that they are told or work out (such as the number of times they have the letter “N” or “T” in their name). Body and hand activities with both discrete and continuous are used to encourage students to imagine and gain mental models of numbers as sets or steps on lines.