you have 9 coins, all appear identical in every way.
but one of them is a bit heavier than the other 8 coins, which are all equal in weight.
you have an old fashioned balance scale, one with two ears or platforms
making just two weighings, two measurments with the scale (nothing tricky in the wording here, mamish two weighings, each weighing of course consisting of putting some coins on one side and some on the other, doing this 2 times)
determine which is the heavier coin
again no tricks
just logic