This coke can grid drawing provides your students with a real challenge! It will advance your students drawing skills as there is a good range of tones/values and it has lots of detail. This would fit well into still life, pop art or reflections units of work.
There are two versions of this one-page resource. One with the grid lines in place, and one which has little marks on the edge so your students can draw their own grid lines.
You will find numerous grid drawings on The Arty Teacher.