Tina knew that lying about what she said to the kids was mean but like she said threatening their wands was mean and Newt wouldn't like her for it but that's what she did to them truly.
The events in class happened like this
Class had settled down and she sat down on the fence that borders of the classroom to listen to newt talk about salamanders. Why because that's what Dumbledore told him the kids were learning .the lesson ran long because one of the students pet cats started chasing the salamander and it almost left the classroom before someone, newt had forgotten was, there caught it. "Tina thanks" he stuttered, as he just stood there looking at her. she froze there thinking why is he looking at me. After a few minutes of looking at each other she said out loud" Oh the salamander".she handed newt gently back the salamander,and gathered her jacket and work stuff up,and left the classroom. so she wasn't late for work.