Not the science of sketching (although I did learn some useful techniques) but sketching scientific stuff, like rocks and bugs, at the American Museum of Natural History, for two full days!
They provided each participant with
Strathmore Drawing pad (to keep);
Staedtler Mars Lumograph black pencil set (six pencils) (to keep);
Prismacolor Premier colored pencils (12 pencils) (to use)
Pentel Arts oil pastels (50 sticks) (to use).
We learned about sketching and then went to different areas of the museum to sketch.
Occasional Observations of Traveling Technology Coach 