This exercise was to use black and white paint only, and to focus on tonal values (the differences between light and shade). It is surprisingly difficult to identify tones. You can have two different colours (say red and blue) but they can be the same tone – so how do you differentiate them if you are just using shades of grey?
Really difficult, I imagine. Did you use a red viewing filter?
It was a bit tricky. I didn’t use any filters, I was painting this from life. Perhaps rose-coloured spectacles would help 🙂