As a tutor, I was struggeling gaining the attention of my students. I came up with this clock to help me out. It rewards the students when they give a right answer, by skipping a minute in time. Since the one and only thing the students want, is the lesson to be over sooner. Let's be real about that.
For a lot of student it's hard to stay focussed while making homework. This clock takes over a little bit of planning, by giving alerts when a break is allowed. This way, students don't have to totally rely on their self-discipline.