Jugs and Jars exercise - this turned out to be a lot more challenging than the books and boxes exercise. I had two bottles, a jar and two jugs arranged together.
I started off quite confidently but soon found that the different elements didn't line up properly, so there was a lot of rubbing out and re-positioning to be done.
The main lesson from this, I feel, is to look not only at the individual objects but also their relative positions, and the spaces in between them. I also found that by starting off with light dotted lines using a B pencil, it was possible to get an overall outline of the group; then I began working on the more detailed elements, finally working with a softer pencil to do the final lines.
On the whole, this was a very worthwhile exercise, and I definitely found my confidence growing as I went along. However, I can still see that some of the shapes are not exactly right (eg the oval lid of a jar seen side-on), so there's plenty of room for improvement.