A piece of chocolate
Some mint leaves
A covered jar
Test whether a piece of chocolate, which is left 20 minutes in a jar with some leaves of mint (without letting them touch), takes the mint flavour.
We put into the jar a piece of chocolate and two/three leaves of mint, being sure they don't touch each other. We waited 20 minutes. Then, we opened the jar and some students tasted the chocolate.
4 students out of 5 said the chocolate had a strong mint flavour; one student didn’t perceive it.