Life drawing in costumes

I went to the life drawing class for practicing drawing skeleton figure but I couldn't realize that Thursday is costume day until the model was on the stage with wearing the costume looking like dancer's something..
I couldn't really practice for today's test though
I got some drawings I like.

Dancing with a skeleton

was the practice for contour line and skeleton figure drawings.

This is a figure drawing in my usual style.

Since last week I feel frustrated everytime in the life drawing class. The curriculum seems to bring me backwards like going back to the past. I'm really afraid lest this year will be useless at all.