Now, I broke out my Positive Discipline book just for you, Dr_Zoidberg, because the minute I read your post, it seemed to me like you’ve got a bad case of manipulative crying on your hands.
The main idea behind the Positive Discipline series is that bad behavior stems from four major mistaken goals: attention, power, revenge, and helplessness.
Now, applying what I know about positive discipline, here are some suggestions for dealing with these things…
If she’s seeking attention, then the best thing to do is walk over when she is crying, touch her shoulder and give her a tissue. Then if you need to, ask that she stay after school and tell her that you’re concerned about her feeling upset. Let her talk. If she denies it, then tell her what you’ve noticed in her behavior, “Susie, you might not feel that there’s a problem, but I’ve noticed that you are avoiding me in class and look sad. What is going on?” (don’t ask “why” as it seems accusative and invites excuses rather than an assessment of the situation). Offer to bring the class in on it to discuss how to resolve the problem. If she agrees, the students are pretty well-tuned to how they would feel in her shoes and they’re probably sick of it too. If she doesn’t then tell her that you assume this means she has worked out how to resolve it herself and that you will not be seeing her outbursts any more.
If she’s seeking power, give her a limited choice so she feels like she has control over the situation and so you can still resolve her problem - “Susie, I see you’re upset. Would you like to tell me about it now or wait until after school.”
If she’s seeking revenge, then call her on it. “I know you must still be upset with me over taking your pencil box away. Do you have any ideas what we can do the next time to make sure something doesn’t distract you from class?”
If she’s feeling helpless because she doesn’t think she’s a good student and being punished makes her feel even worse, let her know that what you did is a classroom rule and that you have confidence that she has learned from her mistake and will do better next time.
The book also suggests that getting the students together and talking about when they cry and how they deal with it and how they can help others who are crying. You could even give them situations like, “Your friend thought they were going to get a high score on a test, but they didn’t so they start crying. What would you say to them to help them feel better?”
You might even go over the rule for confiscating things and to see if they understand why you feel its important enough to make a special rule about it and perhaps see if they can think of a consequence that works for all of you. My students have had some suggestions that worked better than the ones I had thought up for doing things in the classroom. You’d be surprised at how much more they follow rules that they have a hand in discussing and establishing.