Some examples to get you started...
A mole is...
...58 g of salt
...18 g of water
This is a good activity to do for Mole Day (celebrated October 23 - sorry to be late in sharing, you'll have to save it for next year!).
I would leave this as an extra credit opportunity for my students, as it's really beyond some of them. But, if you work with older or higher level students, go ahead and make them all do it!