Matilda

The Trunchbull was teaching again, and she tested a kid on his 3-times tables. She said to him to recite the 3-times tables backwards. Ms. Honey told the Trunchbull that there was no point for teaching multiplication backwards. But, a kid looked at the chalkboard and saw a floating chalk writing something. The Trunchbull looked at it, and it wrote that she should give Ms. Honey her own house back. Then it wrote, "I'm watching you, Agatha Trunchbull." Who could it be?