As a mom of 2 (4.5 yrs & 1.9 yrs.) and an experienced preschool teacher, I recommend you that reach out for some help to nip these behaviors in the bud. You might look into Early Intervention or go through your local public school system. An evaluation of his behaviors by qualified professionals will lead you in the right direction. It would be helpful to think as the parent of the more mellow child who is on the receiving end of your child's inappropriate behaviors. These ARE the emerging behaviors of a young bully. At his age, 2.9, you are obviously preparing him for his first large group experiences in a preschool setting, whether it be next fall or the following. Children at this age are generally self-centered little beings lacking empathy. But by this age, most children have had their own experience of being knocked down by another (whether it was accidental or not) and have experineced, usually through books or videos, the loud and sudden roar of a lion or grizzly bear. Each child has their own interpritation of the experience but, more often than not, the child does not liked getting knocked down - it is frustrating and it can hurt. A loud and sudden (and especially unexpected) noise can be jolting and scary - it can send that quick jolt of adrenaline through the body - envoking instant tears in a small tot. As the Mom, you should be vigilant in your attempts at preventing these behaviors BEFORE they happen, redirect his attention to some other thing or activity, and bring to his attention - each and everytime - how the behavior makes the other child feel (i.e. "bumping his/her body hurts him/her! Please don't hurt my friends" "growling is scary and it's loud, it hurts my ears! Please don't scare my friends.") Show that you value [the friendship of] the other children. Never assume that THEY are friends. I am guessing that some other children choose not to play with yours and make it a point to stay away from him. They would not consider your child their friend. I am speaking completely objectively and am not trying to hurt your feelings, however, these behaviors are concerning to any preschool teacher. I recommend that you make the point to him that these behaviors are simply unacceptable. You may tell him that if he can't play appropriately with his peers then he will not be allowed to participate in these group acitivities. Then, you need to show him EXACTLY what appropriate play looks like. If you feel more comfortable doing this in the privacy of your own home, then do so. Run, jump, sing, dance, build, paint, do whatever you do in your group play settings, and demonstrate what is appropriate and point out what is not, then redirect him to a more appropriate manner of play. It is going to take time, physical effort, and patience. It is going to be exhausting, but it is going to be rewarding as well. Please feel free to reply back directly if I can help more, and good luck.