[soldarnal]

And in particular with probability. It's amazing how difficult it is for people to fake random data.

If you ask half a class to actually perform and record 100 coin flips and half to fake the data, it's almost trivial to guess which is which either by looking for a string of 5-6 heads or tails in a row (which humans almost never have), or by calculating the percentage flips following a heads that are tails (which should be ~50%, but for humans tends to be much higher).