TERBYWONDER is an artist currently based out of Vancouver, Canada who creates figurative drawings and illustrations. I feel like it's just as much of a challenge to create good "sketchbook art" as TERBYWONDER's as it is with any other art.
The IGCSE Art sketchbook that you've been waiting for
This A Level Art sketchbook page by Nikau Hindin shows an analysis of paintings by Janet Fish. The bottom left image is a photocopy; the top right image is an acrylic copy of part of the painting (there is rarely any need for students to slavishly replicate an entire painting – a small portion is enough for students to gain an understanding of the techniques and processes used).
Tips for producing an amazing GCSE or A Level Art sketchbook