This is a lab exercise that utilizes the free online simulation by PHET titled "waves on a string". Many of the PHET simulations require java to run but they are currently updating them to work as HTML5 programs that do not require java so they will run on chromebooks.
This can be done with students working on individual pieces of technology (laptop, desktop, tablet) or in pairs. I have done both and it works well either way. It works well in pairs if you provide structure to how they are to complete the lab together where accountability falls on both students and not one student takes over while the other sits back. Both MUST be accountable for learning.
I have chromebooks for students to use so I have them get out their chromebooks and open the simulation, instructions on how to get to and open the simulation is included on the lab sheet for them.
I provide a few minutes for them to explore the simulation and what t is capable of, the features and to make observations. Then I bring it back whole group to have them provide things they noticed while "playing" with the sim being sure that they bring up the tools and various variables they can use/change as they will be using them to conduct the lab.I recommend going in and playing around with it yourself beforehand so you know what things the students might get hung up on while conducting the lab as well as how it works.
Even if you have students working on individual pieces of technology I highly recommend encouraging students to talk, compare, and converse as learning is very social as students feed off of each other.