A child's maths homework has sparked a divisive debate online after a teacher marked it wrong. In the viral post on X/Twitter, one Irish dad shared a photo of the question which simply asked how many corners a semi-circle had. The child answered that there were two, on the bottom left and right corners – but the teacher said this was incorrect and suggested there were none. Dad Mark wrote: "Hmm. Controversial ruling from the múinteoir here on 'how many corners does a semi-circle have'". His tweet has since been viewed over 800,000 times and was inundated with responses, with one person writing: "I reckon there’ll be some argue this, but your child seems to be right. If the definition of a corner is where two lines meets, but doesn’t specifically state it has to be straight lines, then a semi-circle has 2 corners. But, if the definition being used is two straight lines, then it’s 0. " Another added: "Mmmm… from my memory these are not corners, as a corner requires that two lines meeting, to create an angle of some sort…. It’s a long time since I practiced theorems. They sure look like corners!" Meanwhile, a third joked: "I find it mildly hilarious we have grown adults, some with prestigious degrees in education, deliberating over what seems like 2nd class homework." It comes after another eight-year-old's homework with a very vague question stumped the internet. Shared to Reddit, the question asked: "Janell had 15 marbles. She lost some of them. How many does Janell have now?" Understandably, the child and many full-grown adults were left confused. "The correct answer is 'some,'" one person humoured. How to join the indy100's free WhatsApp channel Sign up for our free Indy100 weekly newsletter Have your say in our news democracy. Click the upvote icon at the top of the page to help raise this article through the indy100 rankings.