dictation

every a (no article is required here) few days, there is(1) are always a dictation test for my son in his school. if he missedmisses some words, or made makes(2) some mistakes. the teacher willl ask him to be dictected be tested again.

(1) 'is always a dictation test...' - the 'a' says singular noun, not plural - so the verb also needs to be singular form

You could also write 'every few days there are dictations tests'

(2) you are using present tense, so must keep it consistently; 'missed' and 'made' are past tense, they should be 'misses' and 'makes'.  I think these are called 'habitual present tense'