Last week I did an activity with an A Level Biology group that demonstrated the concept of genetic drift. Genetic drift is the idea that in small populations, allele frequencies can change as a result of random selection, rather than only natural selection.
The activity uses two different colours of Skittles to represent different alleles. The population starts with a frequency of 0.5 for each allele (1:1 ratio), and as you run the model, selecting individuals at random to pass on their alleles, you find the frequency changes over a few generations.
There’s a worksheet I made with instructions for students and a couple of questions at the end. Download it here.