I took the video below using a Coke Zero bottle, shaking it and opening the lid to produce lots of bubbles. Then, I used the Vernier Video Physics app from my iPad to track the level of the bubbles as they popped. I had to adjust the points and make them a little lower than where they were, because the level of coke was also rising, but if you pause on the y-t graph you get a pretty nice exponential curve.
Below is the graph you get for y-t using Vernier Video Physics.
This is a great simulation and makes excellent links between the random nature of a process like popping bubbles in coke with the random nature of nuclear decay. As students will notice that the decay rate for both radioactive isotopes and other random events like the bubbles popping decreases with the number of bubbles left in the bottle, or undecided atoms left in the sample, they should understand that nuclear decay is also a random process.
It is indeed something they can also try at home and it is more pupil friendly and ethical than using the decay of beer foam.