The letters 'tch' make the same sound as 'ch' at the end of a word.
It can be hard to know whether to put a 't' before the 'ch' or not, but there is a rule that can help.
If there is a short vowel sound just before the 'ch', then put in a 't' as well.
Otherwise just use 'ch'.
(The vowel sound in 'bench' is short, but there is an 'n' between the vowel and the 'ch', so you don't need to add a 't')
Of course, there are always exceptions to a rule, and here are three words that ought to have 'tch' but don't!