"Look out! That old abandoned well is very dangerous, Huck. I think that it should be capped so that nobody could fall in and kill his self." "Ah, shucks, Tom, let's climb down and see how deep it is. I'll bet it is a mile down to the bottom." If we assume that it is not possible for Tom or Huck to climb down into the well, how can they determine the depth of the well?

Tom and Huck will see in this section that the distance an object falls depends on the length of time it falls. When one number is related to another, it is often beneficial to be able to state that relationship. In this section, Tom and Huck will see that we call this relationship a function, if there are no "fickle pickers."