By her own admission, Ms. Norbury is a pusher. (No, not drugs.)
Being a pusher isn't necessarily a bad quality. In fact, for a teacher or coach, it's often a great quality. The thing is, Ms. Norbury's not a very good pusher. As she tells Mr. Duvall (an equally ineffective adult, BTW), she pushed her husband into law school, and now they're divorced.
Ms. Norbury pushes Cady to flex her math muscles. First, she tries to get her to join Mathletes:
MS. NORBURY: Cady, I hope you do join Mathletes, you know, because we start in a couple weeks, and I would love to have a girl on the team, just, you know, so the team could meet a girl.
Cady blows it off. Next, when she notices that Cady's failing her class on purpose to cozy up to Aaron, Ms. Norbury keeps it real with Cady and tells her not to dumb herself down for some guy. That doesn't stop Cady. Ms. Norbury's tuned into her students and means well, but, as a pusher, she's not cutting the mustard.
Until the girls go wild, that is. When Regina drops the Burn Book on North Shore, and the junior girls go boom, Ms. Norbury's forced to take charge. She leads the girls in a clique-busting workshop at Mr. Duvall's request, and she even doles out some helpful advice:
NORBURY: […] You all have got to stop calling each other sluts and whores. It just makes it okay for guys to call you sluts and whores.
In true Norbury fashion, though, the workshop is eventually derailed by the students. Janis tells the entire class about her and Cady's plan to ruin Regina's life. Regina storms out of the workshop. Regina and Cady take their beef to the school's front yard. And Regina gets hit by a bus.
Ultimately, Ms. Norbury does get Cady to join Mathletes, and the junior girls' cliques do collapse upon themselves like so many dying, back-biting stars, so that's good. At the same time, she's investigated by the police for dealing drugs and one of her workshop students gets hit by a bus and breaks her spine, so… when it comes to Ms. Norbury's effectiveness as an adult in this teen-dominated Girl World, we're going to be kind and call this a draw.