Best closed syllable word:
The closed syllables are the syllables where vowels are closed by one or more than one consonant. As the vowels are closed hence the vowels are spell in short sound.
We can take some examples of closed syllable here, like bat, cat, mat these are closed syllable where the vowel (a) is closed by one consonant. For more than one consonant the examples are wash, cash etc.
So, basically as the vowel in short is closed syllable , any student who knows this can easily identify words while reading and spelling. While reading if the student come up with some word of which he is unaware then also she can understand that as the vowel is closed by consonant it will spell short sound and can easily read the word. Hence, in the same way we can conclude that the word best is a closed syllable.
Note: Refer the attached image for clarification.
