I think I did fairly well on drawing these as 3 dimensional objects, but my values are too light, esp on the tomato and apple. The shadows were easier to see on the onion, since it had a shiny surface. The tomato was the most difficult for me as it was a deep red throughout and not uniformly spherical.
Drawing using short strokes is very helpful to me in trying to learn to sketch - but I need more practice with that and with distinguishing values. And with applying chiaroscuro to various shapes and combinations of shapes within one object.