"one is not required to forgive just because someone apologized, they forgive when they're heart is ready to forgive" >>>>> This is actually SO IMPORTANT.
Kids need to be thought when to apologize but at the same time know that sorry doesn't just magically fix everything. That their actions can have an effect on other people and that forgiveness is not guaranteed just because you're sorry. It should be something you do for the other person's sake in a sincere way not something you do to feel better about yourself.