you should be looking as the learning of mathematics… In all likelihood you will be focusing on two or three lessons (or indeed particular aspects of those lessons), but the key will be your exploration of the learning of students based on the evidence from your lessons (with illustrative examples in your portfolio)

[extract from the assignment handbook] The 2800 word submission provides a critical commentary/evaluation with supporting research evidence on the development of your pedagogic skills and the Standards you have achieved.