It is a pretty good likeness of Calvin, Beth. There are some slight proportion problems but they are very minor and you got his features dead on so it is easy to recognize him. Your values are pretty strong and it looks like you did it on some kind of brown paper or something like that. You might want to try using a white color pencil for your highlights and the tone of the paper as the mid tone, this would make your sketch really pop. This is something that I have been doing with my own sketches and it is always impressive looking.

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