Have you ever come across a sentence such as “They should of fired the coach” or “I should of known better”? I’ve seen both of these sentences recently on Facebook. What kind of grammar is this?

Well, it’s actually a common mistake - it’s not grammatical at all! It should be “They should have fired the coach” and “I should have known better.” So, why is this mistake so common?

When someone speaks the contraction of “should have,” which is “should’ve,” it sounds just like “should of,” so some people write “should of” because that’s what they hear!

While this mistake is most common with “should,” it can occur with other modals as well, such as “could” and “would.” Keep an eye out for this mistake committed by native English speakers and try not to repeat it!