Typically, when the Neighbors page displays a very large distance between you and the school, ClassroomParent was not able to geocode (assign a longitude and latitude) to either the school or your address.
The best way to attempt to fix this is to edit your address, which forces the system to attempt to geocode it again. You can do this by making a small change (i.e. changing Rd to RD) or making a large change, saving the address, then changing it back and saving it again.
After changing your address, return to the Neighbors page. If the number is still large, let ClassroomParent Support know and we will look into the matter.