So I was doing reviews and the days of the week came up. As I entered ‘Tuesday’ I got the ‘you made a mistake in your english’ notification and wondered why. Turns out some names of the days of the week are so similar that they’ll be considered correct even when they aren’t sometimes. Very embarrassing. Obviously I should’ve learned the names of the days better, but I was kind of convinced I knew them perfectly so don’t make the same mistake! 
In short, make sure you type the meaning of the days of the week 100% correct! 