portrait of my mother direct observation

this is a 18x24in charcoal drawing I was assigned to do for my drawing 2 class. took around 5 hours to complete
please critique!

Just 5 hours?? You handeled the light and shadow areas very well. Did you draw it after photo or live modell?

she sat there a lot of the time..sometimes for longer durations than other. and other times i would just add light tonal layers while she did not sit there. I did not use a photo though.