Workshops generally require anything from a 3 to 4 hour half-day to a 7 hour full day. These are hands-on sessions where everyone has a go at the chosen topic with guidance and instruction. All the topics in the demonstration section above are perfectly suitable as workshops. Below also are a few more suggestions:-

Perspective – A more comprehensive hands-on look at this subject.
Colour – Hands-on theory and practice.
Composition – Applying design principles.
Sketchbook – The use of sketchbooks in the creative process.
Creative Process – Some keys to invention and visual creativity.
Visual Grammar – The artist’s raw material explored.