In the last Hacking and Kids post, I talked about an activity you can do with kids when you don’t have a lot of time or resources. The key idea was to have fun and learn a little bit about open and closed loop control. One of the things I usually briefly mention when I do that is the idea of a design trade: Why, for example, a robot might use wheels instead of legs, or treads instead of wheels.
Engineers and makers perform trades like this all the time. Suppose you are building a data logging system. You want precise samples, large storage capacity, and many channels. But you also want a low cost and low power drain. You might also want high reliability. All of these requirements will lead to different trades. A hard drive would provide a lot of space, but is more expensive, less reliable, larger, and more power hungry than, say, an SD card. So there isn’t a right choice. It depends on which of the factors are most important for this particular design. A data logger in a well-powered rack might be well served to have a terrabyte hard drive, while a battery powered logger in a matchbox that will be up on the side of a mountain might be better off with an SD card.
We can all relate to that example, but it is pretty boring to a kid. You probably can’t get them to design a data logger, anyway. But if I have about an hour and a little prep time, I have a different way to get the same point across. It is a modified version of the classic “egg drop”, but it is simple enough to do in an hour with very little preparation time.