Now start the second I + C + D sequence below the first. Since I is continuous by definition, begin
the next squiggly line at the time the I period ends in the first sequence, and then draw C for another 40 min, D for 20 min and another vertical line. At this point I would normally shout at the students, saying something like: “DON’T THINK! Just draw I+C+D,I+C+D, over and over until you have gone past the second vertical division line