Every once in a while, I plan a lesson that I am sure will take the entire class, then I look at the clock and somehow there are still 15 minutes left. It's not really enough time to start something new, but it's definitely enough time for a room full of middle schoolers to find their own entertainment. When I was a newer teacher, this used to stress me out. I felt like I needed to have every minute of every class planned, and if we finished early, I had somehow planned the lesson badly. I would scramble to come up with something else for students to do, or I'd stretch out the lesson I had planned just to fill the time. After 16 years of teaching, I've accepted that sometimes lessons just don't take as long as you think they will. Sometimes students understand something much faster than I expected. Sometimes an activity that took another class 25 minutes takes this class 15. Sometimes I planned for a great discussion and my students have absolutely nothing to say. ...