The letters 'ck' at the end of a word make the same sound as the letters 'c' or 'k' on their own.

The ck rule is  -  if there is a k sound at the end of a word and it follows a short vowel sound, it is spelt ck. If it follows a long vowel or consonant, it is spelled with a k

clock has short vowel sound so it uses ck

clock

Book has a short vowel sound so it uses k

book 

In this worksheet you can practise reading and writing words ending in 'ck'.