Look at the word. Does it have a closed syllable or an open syllable?
so
open closed
Words are made up of syllables. Two kinds of syllables are closed and open.
A closed syllable has one vowel and ends with a consonant. It usually has a short vowel sound.
desk: short e
kit / ten: short i / short e
An open syllable ends with one vowel. It usually has a long vowel sound.
go: long o
he / ro: long e / long o
Some open syllables end with y. The y makes a long e sound or a long i sound.
sky: long i
ba / by: long a / long e
The word so ends with a vowel and has a long vowel sound. So, it has an open syllable.