The idea is that we hang a slinky vertically and pull on it. Then we time how long it takes for ten cycles. We vary the number of coils that we allow to hang.

coils is the number of coils.
time_10 is the time (in seconds) it took for 10 cycles.

What do you expect the the pattern to be? If you have fewer coils, will the waves be faster, or slower, or the same as with more coils? Why?

If you know about harmonic motion (say, the frequency of a hanging massless spring with a mass on the end of it), how does this relate?

How does the frequency of this "hanging wave" depend on the number of coils?