Do you ever go to the gym and just stand around ?

Yes, but I work behind the front desk. When I am on the other side, I work out. That said, the instructor should have never screamed like that. It can be very intimidating the first time you come to a class. She should have been on time or early if it was her first time, but that reaction was uncalled for.

Well, playing devil's advocate, perhaps the newbie was pretty scared and didn't know what to do when she walked in late. Like a deer in headlights. the instructor should've WELCOMED her into the class and told her where she could go and what they were doing and/or tag team with another member to catch up. To yell at her was ridiculous and cruel, especially if she was new. INSTRUCTING her would've been more appropriate, and perhaps a gentle reminder of class time. She'll probably never come back and that could've really hurt her attempt at becoming a healthier person. Sure would not have encouraged me to embark on a new and difficult journey. The instructors are supposed to be there to support your journey, not derail it. it'd be different if she were a repeat offender, but even then you call her out after calss, not during in front of everyone.