One child in my class, Rosena, is always trying to control the other children. She tells them what to do and when to do it. She even thinks she knows what's better for them than I do! I'm worried that this bossiness may escalate to bullying. What can I do about this behavior?
I'm sure this behavior annoys you (as it probably would most adults), but let's think about the bossiness as Rosena's interpersonal problem, and how we might help her. Also, I wouldn't worry about her resorting to bullying. You didn't describe her as a child who seems mean or angry. Children who bully want to scare and hurt others, but it doesn't sound like Rosena has this in mind at all.
Children who boss others aren't popular — that's the problem. Peers soon discover that they don't like taking orders and shun the child who does this. Rosena will grow more lonely and upset.
What You Can Do
If Rosena complains that someone won't play with her, help her think through why the other child might not want to spend time with her. Don't tell her (which is often our tendency), but patiently guide her toward understanding.
Ask any child she's bossing, "Do you like when Rosena talks to you like that? Would you do it if she asked nicely? Show her how you would like her to say her words. If you don't want to do what she's saying, what could you say to her?" Teach her classmates to politely hold their own. Then you can whisper a friendly reminder to Rosena about letting other children do things their way.
If Rosena gives you orders, let her know that children don't tell grownups what to do, and that grownups are in charge. Never do anything that Rosena demands, but always do the things she suggests or requests-perhaps with a smile and a compliment.
Ask a child she's bossing if Rosena is fun to be around, and how she could be more fun. Ask if she's making the child feel good, and how she could make him feel really, really good.
If these strategies don't seem to work, tell her (privately of course) that she'll have to play away from the other children for a little while so they can have turns deciding things. Let her know that she can't make all of the decisions.
Assertiveness and persistence are certainly great qualities. Find roles where leadership or assertiveness are needed in other forms. I'm sure Rosena has other attributes besides bossiness. Is she sometimes funny? Kind? Particularly good at something? Are there times when she's cooperative with the other children? Quick! Reward this behavior by giving her a grin and a hug.