How do I track the achievement of a specific group of pupils?

The Assessments tracker website contains a 'Summary Analysis Report'

This is a bar chart showing the combined performance of the selected group of children across all of the features which make up the Little Wandle curriculum at a particular assessment point. This can be used to show how individual classes are performing. You can also filter on contextual details such as FSM/gender, etc to demonstrate how select groups are performing.