I appreciate your honesty.

This sounds like an opportunity to practice emotional mastery. They are children, so they don't have a lot of emotional intelligence because they simply lack guided experience. Your job is to show them how to manage their energy and emotion. And I think a lot of that involves recognition. If their emotions are validated "it's ok to feel angry or sad, so go ahead and tell me what's upsetting you", and their energy is redirected to something which is manageable -- say, like park activities -- then that might make a difference?