Maths lessons don't get much more terrifying than this.
A French maths teacher has been suspended after he showed the torture film Saw to a class of 11-year-olds.
According to reports on Radio network Europe 1, Jean-Baptiste Clément told his pupils: "This will be your first horror film."
Unfortunately, not all of the children were impressed, or as ready to abandon the safe world of sums as readily as Cary Elwes saws off his foot.
Some parents complained to the school, which is in Hauts-de-Seine, in the north-western suburbs of Paris. One father said his son came home that day "visibly in some discomfort".
"I asked him and he told me his maths teacher had shown them a horror film during class. At the moment the teachers are having staff meetings and parent-teacher meetings, so their classes are cut short and interrupted a bit."
In response, the school gave Mr Clément a one-day suspension while it conducted an inquiry.
"We're in the process of seeing what sort of legal measures we might be able to take in this case," said a spokesperson for the school.
Saw tells the story of a mysterious serial killer who forces his victims to mutilate themselves and others as part of a cruel game.
If Mr Clément had been thinking smartly he would have picked the 2007 horror flick Fermat's Room. At least it has a maths theme.