We were quite into analysing the behaviour of teachers in Year 11, and we made some startling discoveries. Among them (the rest can be found in other areas of the Yearbook), is the Patience Theory. The three 'graphs' below outline the basics.
The first one plots time against patience. As you can see, if the lessons ends (at 3:05pm) with spare patience, you have wasted all that patience there. The second one shows what happens if patience runs out before time runs out. You get a detention. If you can time the expenditure of patience with the bell exactly, you get a perfect graph, as the right picture shows. This is extremely difficult, and as most teachers don't take kindly to being manipulated in this way, you'll likely accelerate patience loss trying to do it. That'd produce a complex curved graph.