In many AS physics exams, you're very likely to be asked how to measure the speed of sound in laboratory conditions. Usually, this will be in the form of a long answer, so you'll want to have the method pinned down perfectly in order to win as many of them as possible.
You'll need to draw the diagram, too.
Method
The signal generator produces a simple, low-frequency square wave for the speaker to sound, which produces a short pulse of waves at the natural frequency of the speaker cone.
The pulse from the signal generator triggers the trace on the oscilloscope when the square wave becomes positive
The microphone detects the pulse of sound and the oscilloscope shows its trace. The time taken for the sound pulse to travel from the speaker to the microphone is measured using the time-based scale on the oscilloscope, from the start of the trace to the arrival of the wave.
The distance d between the speaker and the microphone is measured, and the microphone is then moved to a new position. The new distance and time are taken. This is repeated until there are at least five sets of data for a reasonable range of values of d. You should repeat measurements and take averages for each distance.
On the graph of distance against time, the line will be straight and the gradient will be the speed of sound in air at the temperature of recording.
How to remember it
Make a bullet-point list of each stage within the method, with only a few words on each bullet point.
Practice writing it out from memory a few times, and then move on to practicing writing out the full method about three times. By the end of that, you're very likely to know it off by heart (it worked for me!).