a mean homeroom teacher

It's a rainy day but some of classes are on going. One day a homeroom teacher hit her student because of being pazaway inside the classroom,the child tell it to his mother but the homeroom teacher says she did'nt do that. A recess time came a two girl students tell to her they want to go to bathroom and she said yes. The two girl walking down to stairs, the one girl notice that the rain falling down outside and she decided not to go to bathroom to pee because she remember what her mother told to her that "do not ever go out if a rain falling outside,if you dont want to sick". But the one girl running outside because she want to pee. After that they back to the room. The girl whose did not go to bathroom to pee make a decision to say to her homeroom teacher that she want to go outside again because she really want to pee but the teacher did not give her a permission. When they writting the girl pee in her dress and feeling down because of what happened to her and the homeroom teacher "binatukan" her head. She is very sad fir what happened. The bell ring and some of her classmate go home with their parents. And her mother coming already to picking her inside the classroom. The mother greet "Good morning mam."(with a happily smile but change it to disappointed.) The teacher tell to her mother what happened but she did not tell that "binatukan" the girl. She always pointed out the girl is a liar one with the other girl. The mother feel bad for what the teacher already pointing out. But the mother calming her self and said "next time mam if my child really want to pee please give her a permission because she cannot control it anymore if she really meant it." The homeroom teacher pointing out again and again that her child and other girl lied! Question If you're in the situation. What will your reaction and move?