Recent Life Drawing

Most life drawing classes I go to have artists from all levels, but this term I've noticed that most of them are at a beginners level, which is really good for me! I get to go back to basics and improve on my technique but the first couple of weeks have been frustrating. I can't believe how bad I've been all because I've had my conté taken away from me! I guess I didn't realise how much I rely on tone for accuracy - the above picture was drawn with line only and you can probably see the numerous alterations.