How do I improve my sketchbook to show development of ideas and processes?

The examiner will be looking for critical involvement and reflection with your own studies/progress works and the works of other artists. Treat your sketchbook less like a diary (eg. A list of how you did something) and more like an evaluation - so for a page on a study you’ve done: annotate what process you’ve tried, how effective that was, how you’ll take elements of the process forward into your next study etc. Similarly for an artist research, engage with the artist’s work and don’t simply focus on biographical information; discuss how they’ve used the medium, how you might used their process to inform your own and maybe even look at critical texts on their work.