Mouse and Orange Balloon are having a competition to see who can hold their breath the longest and naturally a stopwatch is needed to time it. This leads to a discussion of clocks and watches, which as the narrator explains, we use for all sorts of things these days, from timing the changing of traffic lights to waking us up in the morning. As we watch a group of kids take some clocks apart to learn about how they work, we find out that it's taken hundreds of years to make clocks that we can depend on, about four hundred years to be exact. The first clocks were very large and not practical for keeping in homes, but the invention of the pendulum led to smaller clocks which could be used in your house. Clocks also have decorative purposes and we learn that pictures on clocks have been around from their beginning. Over time, clocks became better and the demand got larger, so machines were invented to speed up the process, although they still all had to be checked by hand. Eventually, the