Here's one that I see come up time and time again in my classroom... 

The pronunciation of 'ed', as in 'stopped, hunted, laughed...just how do we pronounce these? The ending of each one of those three verbs has its own distinct sound. It's not stop-Ed, or hunt-Ed, or laugh-Ed, so how do we remember the correct pronunciation of these words? Of course, as a native speaker it's second nature*, just like riding a bike! However, for students who are learning English as a second, or perhaps, third language, some rules apply. Now, if you have ever witnessed one of my classes, you will know, that I'm not a firm believer of rules, however sometimes, just sometimes, they have their place, and this is one of those times! 

Click here to watch my short video where I explain the rules! 

*second nature / a habit that has become instinctive