I am teaching 15 year olds basic probability. I am teaching them "experimental probabilities" (eg the probability that it will rain on a given day in August is 0.15) vs "theoretical probabilities" (eg the probability of throwing 3 Heads in a row is 1/8).
When I asked them for some examples of experimental probabilities, a couple mentioned one-off events, like the probability that their team wins their next match, or that it rains tomorrow.
I can't see that one-off events can have a probability other than 0 or 1. They cannot be re-run and hence their is no basis for determining or assigning a probability.
I would like to correct my students if and when they next make this error, but before doing so I would like to make sure of my facts. Is it legitimate, for example, to talk about a 40% chance of rain tomorrow, and if so, what does it mean?