I used to not be able to find the subject of a sentence and I could never remember if the "I" came before an "E" or the other way around.
When I was in grade school, I would always choose the wrong noun as the subject of the sentence. I had this problem all the way through high school. I did not do very well in English in school. I really hated English. All the rules that never made any sense at all, just were not important to me. It was not until I had to take college English that I developed a love for my language. I had one professor who really knew how to teach it so you could really learn it. At the beginning of the term, we of course started with a review of very basis grammar. We were talking one day about how many of us (I was not the only one, I was glad to know that) could not find the subject of the sentence. Our argument was there are sometimes so many nouns in a sentence, it was hard to know which one was the subject.
She looked at us like we were crazy. And also like someone should have straighten this out for us a long time ago. I remember she laughed and said, "It is really very easy". "The subject of the sentence is never, ever, ever, ever, ever, ever contained inside a prepositional phrase." Now I am thinking, "Ok, what in the heck is a prepositional phrase?" Remember, I hated English, so I never really learned how to use it. I think many other students must have been looking at her the way I was looking at her. "What's a prepositional phrase?" She started laughing so hard, she had to step out of the room. Here we are freshmen in college and we knew so little about English. When I think back on it, I find that pretty amazing.
When she came back into the room she asked one simple question. "How many of you hate English?" Very nearly everyone in the class raised their hand. She said, "Ok, let's start from the beginning." I learned more about English during that term than I had all my life. I came to love the language very much and as many of you know, have now become an English teacher myself.
Here is an example: The key is in the living room, over the fireplace, on the mantel, by the book. In this sentence, key, living room, fireplace, mantel and book are all nouns. BUT...only one is not inside a prepositional phrase. When you "remove" all the prepositional phrases: in the living room, over the fireplace, on the mantel, by the book; all you have left is "The key is." So the only noun that can be the subject is the word "key". See, it really is easy!
The second one, the i and e one, I finally mastered by the 6th grade I think.
The rule is: "I" before "E" except after the letter "C". Examples: Receive, pie, and piece.
There, now you know even native English speakers have had trouble with English too.
BTW: She was a very good English teacher and to this day I can't remember her name.