The Worst Witch S03 E05 Learning the Hard Way

"Mildred Hubble spells trouble."

Miss Cackle's young niece, Gabrielle Gribble, comes to the Academy for teaching practice. Suffering from a bit of stage fright, Gabrielle takes Miss. Hardbroom's advice of being tough a little to0 seriously & she becomes a tyrant who throws the entire class in detention within minutes of her first day. Soon Mildred & her friends end up teaching her far more than she ever learned in College.