Here's why:
* Short vowel sounds are typically found in closed syllables, meaning the vowel is followed by a consonant. In "black," the vowel "a" is followed by the consonant "ck."
* Long vowel sounds are often found in open syllables, where the vowel is at the end of the syllable or followed by a vowel.
Therefore, the sound of "a" in "black" is a short vowel sound, similar to the "a" in "cat" or "hat."