woman: miss hammill will put it on very easy. just for it to protect your eyes, so you won't hit your eyes with the hammer or the nails pop in your eyes, o.k.? woman, voice-over: there's no running in the classroom. the limit for that is safety reasons. it's safer to walk in the classroom. if you're running around a table and you hit the chair, you're gonna get hurt. if you walk around the table, you have a better chance of not hitting that chair, and when they understand that limit in the health perspective, it's better-- they can more readily understand why that's a rule. woman: let go of her dress. it is not o.k. it is not o.k. let go of her dress. let go. let go! it's gonna rip. did shannon have the toy first? [boy speaking indistinctly] but shannon was playing with it. can we take turns? yes? hendrick: just as a child's understanding of right and wrong is different from an adult's, so are a younger child's perceptions different from an older child, which is why it's so important to approach aggressive behavior according to t