M&M Demonstration

To emphasise the quantitative aspect of the first order decay process, you can use a demonstration on the visualizer – take 40 M&Ms and place them face up (the ‘M’ up) in a clear Tupperware container. This is the population at t=0. Ask a student volunteer to come and shake the container (gently) for 3 seconds and remove the M&Ms that are now face down – the remaining population is recorded as t_1/2 on a graph. The student then shakes the container for another 3 seconds and the process is repeated – it generally only takes 5 to 6 shakes to observe the exponential relationship between number of M&Ms remaining and t_1/2. Students love the real time demo (and the volunteer keeps the remaining M&Ms). You can relate this to isotopic decay because the M&Ms represent particles (atoms).

Link to The Science House: Radioactive Decay