Calling the museum on Tuesday with a sob story about how you "thought you made a reservation but didn't and can't we please come anyway!" for Friday does not make me feel bad for you. Lack of planning on your part does not make for an emergency on my part. Also, trying to guilt trip the office staff about how disappointed the kids are going to be will not get you anywhere. If the kids are disappointed, it's your fault, not ours. And when we tell you that we'll make an exception to the "two weeks notice" rule and get you in, but that you have to come after 12:30, the correct answer is "Thank you so much!", NOT "Are you sure it can't be earlier?" There are already many, MANY other morning groups headed by teachers who actually had their act together and called in advance. They win, you lose.
The very tired school programs coordinator
PS - The fact that we are talking about 60 middle schoolers in springtime doesn't help your cause.