Cranford has a single high school which serves the entire town. There are several elementary/middle schools scattered through the town. If you are asking about the Cranford school system in general and how it compares to others in NJ, there are several sources to consult.
One is the state's 'report card' site: http://education.state.nj.us/rc/
Another source that many prospective buyers/renters look to is NJ Monthly Magazine's
annual schoold issue: http://njmonthly.com/articles/towns_and_schools/highschoolra
Also, consider meeting with the principal or superintendant of towns that you
are considering -- ask questions, ask to be given a tour, etc.
Feel free to contact me if you need assistance in finding a home in Cranford,
I'd be happy to work with you to find something right for your family's needs.
Prudential NJ Properties