Hi Monica,
Thanks for reaching out!
Unfortunately, you are correct that there is not an out of the box way to validate the user’s age. However, using the custom fields and some JavaScript, you could add this functionality to tickets. We are not able to do customizations like this, but we do have a list of recommended developers who could help you out with the code if you need it.
Another suggestion would be to use a checkbox to ask for the users to verify that they will in fact be of age when the class begins, but of course this would not give you their birthday.
If this is something you want to see implemented in future releases, I would recommend casting a vote in our Feature Ideas forum to let us know. I wish I had a better answer for you, but if you have any other questions, please don’t hesitate to ask!
Thanks,
Jennifer