I know these are just simple cylinders with a piston, but I really like how I can do two labs in one day with this equipment, in two different ways.
First, we use the speaker, tune it to a frequency (they seem to like 440 Hz, which is the same as our bell, and 670 Hz, for a reason that every dang teacher knows now. If you don't, my word, I am jealous.)
Now, when you find the resonances, where the wave constructively interferes with itself, you can use that, along with the wave equation, to find the speed of sound. (Many students get an answer off by a factor of two, which makes for a great discussion.)
Then, we can replace the speaker with a microphone, and do a SNAP. You can see the initial snap, and then, milliseconds later, the echo of the snap of the sound wave that went down the tube. So then again, I ask them to find the speed of sound using distance and time. (Many students get an answer off by a factor of two, which makes for a great discussion.)
I absolutely love it when students get both answers off by a factor of two, for two wildly different reasons.