At the last minute of the last class of the week, the logic teacher said to the class
Next week, if I can, I will hold a surprise quiz in one of our lessons.
The quiz will be about everything we've learned throughout the year, including homework. I'm going to make the hardest quiz I possibly can.
Those who will fail, will have to come to reinforcement lessons over the weekend.
Then the teacher exited the classroom, leaving everyone in slight shock. Some students went to Charlie, a very good student usually, who seemed surprisingly calm. When they came close, Charlie said
Don't worry, no one will have to study in the weekend.
How did Charlie know this?
Clarifications:
- Charlie didn't have any prior knowledge on the quiz, or on the teacher's whereabouts the following week.
- This is the middle of the semester. There's a lot of material
- There are 3 classes of logic a week