Here's why:
* Syllable: A syllable is a unit of pronunciation consisting of a single vowel sound, with or without surrounding consonants.
* Open Syllable: An open syllable ends with a vowel sound.
* Closed Syllable: A closed syllable ends with a consonant sound.
In "freedom", the first syllable ("free") ends with a vowel sound (the long "e" sound), making it an open syllable. The second syllable ("dom") ends with a consonant sound, making it a closed syllable.