This spelling rule applies to the END of words and is only reliable with single-syllable words.
It states that when you hear the /k/ sound at the end of a word AND the /k/ immediately follows a short vowel sound (a, e, i, o, u), it is spelled ck.
If it is preceded by a consonant it is spelled with a -k (desk), and when preceded by a long vowel usually -ke (take) and sometimes -k (creek).
This also applies to the individual parts of compound words (e.g., backpack).
