Exercise 3 Creating shadow using lines and marks

This is a bit of a combination of the old format and the new because the exercises seemed so similar

I was a bit confused by this exercise. Were the squares supposed to have the same tone? That's what I've done, or was I supposed to draw a simple object? This is for the old format course so I did 2 simple objects I picked these conkers up a couple of weeks ago intending to draw them. I think they're a little small for this exercise but I've done them anyway

This is biro,HB papermate,4b pencil and Uniball pen(that doesn't quite fit, bad planning)
Then I used a variety of media for my studies

I think the biro was the most successful though the shadows are a bit dark in places.
Then I got the course material for the new style course and tried to draw the same objects without to many outlines

 I used biro. The position of the objects isn't quite correct as I was focusing on the shadows rather than the lies and I was trying to work rapidly and loosely

How difficult did you find it to distinguish between light from a primary light source and secondary reflected light? I tried to draw what I saw so I don't think it is important where the light or shadow is from but it is important to show it if it is visible. Is that the wrong approach?
How has awareness of tone affected your depiction of form? If you look closely at the tone and represent it well then the form sor of emerges because that is how we make sense of visual images (I think)