Listening to every heart
Planetary observation site.
Bakery, or any restaurant [dealing with quantity and how to anticipate the number of units to be sold every day; what goes into preparation of individual meals...]
Zoo, what it takes to feed its animals...
Grocery stores [again, numbers of units] and also incorporate each student's need to "plan a meal for 10" and figure out what one would require for a five course meal...
all math related.