I was in a secondary mathematics classroom where the teacher asked a class of 12-year-olds to close their eye and imagine two squares. Then,he asked them to open their eyes and describe their squares. Their descriptions were in terms of colour,size,connectedness, and embeddedness. It became clear, as they talked,that some had 'seen'the squares as separate entities,some had them inside one another, some had them connected in a row and one had imagined a cuboid ,the two squares being the front and the back face. Colour had been unimportant to some and very important to others.Yhe teacher then asked the children to say hoe many lines they had used to make their two squares. Answers ranged from five through to eight. Pupils were then asked to see if they could find a connection between their way of 'seeing',the number of squares and the number of lines.Differences in approach were not only welcomed and valued,but ensured that there was a rich ground for comparison and for relating the differences to the initial conception of the task.those who initially 'saw' the squares as separate generated the multiples of four (Figure 2.10) but those who created their