Derek introduces how geometric thinking revolves around the idea of ‘same but different’. This is called equivalence and transformation. Derek explains when it is useful to focus on equivalence and when it is useful to focus on transformation. Visual cues are used in the video to explore how two shapes can be the same yet different. He transforms shapes by rotating cards by ninety degrees or by shrinking them using scaling up and down. Derek tells the viewer that a lot of what is done with geometry is learning about the different ways in which a shape can change and also looking at collections of shapes and identifying various sets of shapes that have something in common.

The next stage of the video looks at subsets in shape similarity during the process of classification, identifying and grouping quadrilaterals and so on. In order to define these equivalences Haylock believes that understanding geometric language is important. Derek ends the video by reinforcing that two questions are always present when looking at this:

What is the same?

How are they different?