Exercise 2 Observing shadow using blocks of tone

I drew 2 white bowls

I'm struggling with the shadow on the inside of the bowl on the left

Maybe this is a bit better (and I've cropped it which looks better)

Hard in charcoal to get the subtlety of shade sometimes. The paper says suitable for all mediums but it was difficult to get an even tone, maybe that's a good thing?

It looks better when reproduced smaller!