If I heard a 911 operator scolding a caller for such as what you did, I'd be seeking her termination and replacement. Instead of scolding, she ought to be commending you on taking the responsibility to properly educate your kid. I've routinely dialed into 911 service as a matter of proofing various communications systems, and the whole point is to ensure that positive communication is established, which is precisely what you did, even if inadvertantly.

I will state this as a matter of fact: 911 operators are there to provide a public service and their efforts are paid for by our tax dollars. Events such as the one you describe are to be expected, even encouraged. You did not do anything wrong, and you did not "inconvenience" or "stress out" the operator. If they were, then they are in the wrong business and need to seek employment elsewhere. The operator is lucky it was not me that made the errant call.

Conversely, abuse of the 911 system is intolerable and subject to punishment.