Here's why:
* Short vowel sounds are usually found in words with one syllable and a single vowel, where the vowel sound is short and quick. Examples include "cat", "dog", "run", "hop".
* Long vowel sounds are typically found in words with:
* Two vowels together (like in "yellow")
* A vowel at the end of a word (like in "go")
* A vowel followed by a consonant and a silent e (like in "make")
In "yellow," the "e" at the end makes the "o" say its long vowel sound.