What exactly is a magnet school?
Do magnets need to learn? Is there a school that teaches them their fascinating magnetic properties? Is that what Magnet Schools of America does?
No it's nothing like that.
Magnet schools (that's their logo above) make the very obvious assumption that all students do not learn in the same ways. So they set out to find a unifying theme or a different organizational structure for students with similar interest. They take the view that this will help students to learn more in all areas.
It all comes down to the theory that students will find such schools attractive.
Sounds like a great idea. Check out a detailed history here.