-Once upon a time there was a group of friends called "modal-eggs", and they were talking about their functions.

Hi!, i'm "Can", and i'm going to teach you how to use me

I can only be use in present tense, and my meaning in spanish is "poder"

The bee can fly, but the dog can't

Now meet my friend "could"

Hi, i'm "could" and you can use me in past, my meaning in spanish is "podía-pude"

i couldn't sleep last night

Hi there, i'm "may", and you can use me to indicate possibility in future.

Now is my turn...

It may rain later

And finally, i'm "should"

You need me when you want to make a recommendation. 

You should run!

with you I was able to learn the function of some modal verbs, now can I be part of the modal-eggs?

After a long time, the modal-eggs accepted the egg into their club and called it "might".

After a long time, the modal-eggs accepted the egg into their club and called it "might".

And they were happy ever after...