In this lesson, my students took a painting surface measuring 8"x 12", and divided it into six 4"x4" squares. They painted a red delicious apples six times, only being allowed ten minutes per apple.
They could spend some time mixing their colors before the first timer was set, using their View Catchers to judge where the most saturated reds were, and what other colors were actually there- not what they assumed they'd find. I implored them to use red's compliment (green) to de-saturate the reds.
The top photo is of all the apples painted by all the students, while the second image is of just one student's six timed studies.
Next, everyone had to paint one apple behind another. The idea was to create a sense of distance by under-reporting the darks in the distant apple, and placing their most saturated reds on the closer one. They also slightly blurred the edges of the one in the rear.
I think they did very well with this exercise, and they seemed to find it intriguing.