Our first 'real' drawing assignment of the quarter (after the portfolio) is due today. It's a really good sketching exercise, and involves copying sketching styles and drawing products from photos. The idea (and I buy into this) is that by copying something, you pay more attention to its details.
Here's one example from my ten sketch pages. It's one of my favorites because rendering lights is a lot of fun and the product that I copied is very design-y. I made a conscious effort in almost all my pages to include people, or put the product in context. I picked up on the importance of that at eleven... its hard to do, but very worth it.
You can see the complete assignment here.