Open syllables are syllables that end with a long vowel sound and are spelled with one vowel letter. The vowels in these syllables are not closed with or protected by a consonant.
A good example of an open syllable is the first syllable in the word "to-tal." Additionally, there are a few English single-syllable words that are also open syllables, like the words "no" and "go."
Open syllables are one part of six syllable-spelling conventions that were regularized by Samuel Webster and first used in the division of syllables in his 1806 dictionary. These conventions are useful for teachers, as they help students remember how to pronounce vowels when speaking or include double letters while spelling words.