As Linda mentioned, the more excited the children get, the more hyper puppies tend to be
This is prefectly normal doggy behaviour but she needs to learn that it is not all that acceptable. Can you get the children to 'be trees' when she starts? Get them to cross their arms in front of them and stand completely still looking at the sky - this way they will be very boring for your puppy and she should rapidly loose interest in them.
Here are a few more tips on controlling puppy biting (longish, from the Boxerbytes site

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Biting and chewing are perfectly normal behaviours for a puppy. Pups bite in play as it is all part of the learning process - they need to bite in order to learn bite inhibition. They also bite as they lack the self control of an older dog and get very excited when playing. Puppies chew as they are teething and chewing eases the pain of the new teeth coming through.
When your puppy bites you there are several ways you can handle this. Many people have success with giving a little 'yelp' or 'ouch' when a puppy nips them, pulling their hand away. You can also immediately stop playing with the pup when he or she bites you, do not scold your pup or say anything, just walk away and ignore them for a couple of minutes. It does not take them long to learn that if they bite the game stops. Pressing down very gently on your puppies tongue when they bite and also be used. This is very unpleasant for a pup, but totally harmless. Folding their jowls in on their teeth, so they actually bite themselves is also effective.
Do not worry too much about puppy biting, they will grow out of it (they will, we promise) and with sensible training your pup will learn self control and bite inhibition. Never, under any circumstances, hit or strike out at your puppy when she bites, this sort of punishment is not understood by your dog at all.
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