If a teacher fails to turn up to class it's usually a cause for celebration for students as they dash off to enjoy a few precious hours of freedom.
But what happens when it's the other way around and a teacher is left all alone with no pupils to impart their knowledge to?
This is what happened to Florida-based professor Adam Heath Av table who took to Twitter to share a story about when he got stood up by his students - and it is both hilarious and heartbreaking.
Adam Heath Av table, who is a storyteller and comedian, according to his Twitter bio, took to the social media site to complain after nobody turned up to his class.
He decided to document the day via Twitter using the hashtag #Classwatch2017.
The tweets soon went viral, with over 2000 people liking them and hundreds re-tweeting.
When Adam was confronted with an empty room, he began to start doubting himself and questioned whether he had told his students that there was no class that day.
Adam bemoaned the quietness around him and said that every time he heard a door open he smiled and prepared himself to be faced with students - but it never happened.
After 45 minutes, he decided to check whether he had locked the classroom door and prevented his class from being able to get in. It wasn't.
He then started wondering whether everyone in the world was dead or if there had been a sudden zombie attack and he had survived it alone in his classroom.
The comedian's tweets began to get funnier as he commented on the fact that a bird was outside his window and that he had invited him in to learn about algebra. But even the bird declined and flew away.
As more time passed, Adam checked his email to see if he had missed something and said his inbox was empty.
The poor teacher had even got candy for all of his students, but said that he would have to eat it alone.
After a long time sent his boss an email asking where all of the students were, but received no reply.
Ninety minutes in, he heard the door open again but realised it was a false alarm and vowed to pack up and go home.
It was then that two students walked into his classroom ready to be taught with no explanation for their lateness.