Working hard?

One day I took a picture of some of my students. They were working hard, as usual. I like the moment in which they look concentrated on it. It makes me think 'Are they really learning?' 'Was my explanation good enough?' 'Am I really motivating them?' Maybe not many students know this, but teachers are always questioning themselves, because there is not only one teaching method, but as many as students. I would like to know what some of them think of it. Does anyone dare write back? Thanks

J Tomás (EOI teacher)