Students form pairs, with each partner having the same function. Pairs attempt to find the function that fits the description. This may be an iterative process. You've got it. That can't be the function because it doesn't satisfy a particular aspect of the description.
Additional rounds give the students practice matching functions to descriptions.
Prerequisites will vary depending on the functions used. Depending on the kinds of functions used, students could be asked to find the exact function or merely a generic version. The purpose of this exercise is to build the skills and intuition about functions that students need in order to, for example, choose an appropriate function form for a collection of data points. It decreases rapidly when x 1, the function increases rapidly in value. Its value is 0 when x is 0, and decreases sharply as x gets more and more negative.