Here's why:
* Short "o" sounds: Words with a short "o" sound usually have the "o" in a closed syllable (a syllable ending in a consonant). "School" has a closed syllable "schoo."
* Long "o" sounds: Words with a long "o" sound often have the "o" in an open syllable (a syllable ending in a vowel) or have a silent "e" at the end.
Let me know if you'd like to explore more examples of long and short vowel sounds!