|There is a Spanish sentence, quite "famous", by the way, among students, that somehow can help you distinguish these three words. Because... Yes! For some strange reason, native Spanish speakers, from 8 to 10 years old... or older! also need to learn how to spell these words.|
So, the sentence is:
"Ahí hay un perro que dice ¡ay!"
"Ahí hay un perro que dice ¡ay!
"(Over) There there is a dog saying ouch!
Well, the sentence is not specially brilliant, but it can be quite useful to differenciate the use and meanings of these three words.
Hope this helps!