Associate the long and short sounds with the common spellings (graphemes) for the five major vowels.

There may be fourteen-ish vowels in English, but we only have five ways of spelling them. So, make sure students understand every sound that each vowel can make. If they understand that 'I' can be /i/ or /ɪ/, they'll finally be able to make sense of Mississippi when they inevitably learn how to spell it.