A favorite drawing from yesterday's life drawing session

We had a discussion today in our art discussion group about how the drawing sessions we're doing are supposed to be practice only...with no eye on "product". Just the same, I couldn't help but feel like I wanted to keep this one. She was a really good model and I am fortunate I will be working with her again. I was satisfied that I got the essential information down in just a couple of minutes. This model often used a downward look that felt a mixture of woe and contemplation. I often wonder ....just what IS the model thinking?? Does anyone have any ideas?