When do I need to write 1 "s" or two "ss" in a word?

Still now, the way I figure this out is still the same as when I was 6 years old and my teacher gave me this method. S is a very Sensitive letter and Vowels are very naughty. When they surround an S, the vowels cannot keep themselves from tickling it and so it makes the sound "Zzzzz" . Because the S does not want to make that sounds, it asks a friend to join and together they can counter attack the vowels and make the sound "Sssss".In conclusion, always have a look if the sound "Sssss" is surrounded by two vowels or not and that will let you know if the S needs reinforcements or not. For example: "Tasse" (mug), "Pousser" (to push), "Poisson" (fish)The consonants are very well behaved so they do not tickle anyone!For Example: "Test" (test), Question (question)