Another helpful spelling rule is:
If a one-syllable word ends in a short vowel and is immediately followed by the consonants f, l, s, or z, double the consonant.
- fluff, puff, whiff, off, buff
- bill, hill, hall, mull, fill, tall
- mass, kiss, chess, less
- jazz, buzz, fuzz
(The letter /a/ does not always have the expected short sound.)
Remember, these rules are very helpful for students with specific learning disabilities in making sense of spelling and reading.