A lot of Spanish learners (and, no doubt, other Latin learners, too) have problems pronouncing the vowels (a, e, i, o, u) correctly. Often, they either pronounce it as in their own language, or they confuse letters, especially e with i. Last year, José Alberto, from IES Los Tarahales, and I were working on a chart to hang on the classroom wall to help the children remember the right pronunciation. Although pronouncing vowels doesn't really help with general pronunciation, it is very important when they are asked to spell words, or when words are spelled out to them.
Unfortunately, we never did quite finish the chart in time. Although not perfect, we're sharing it here now in case some of you need something like it for your classroom. The same document is also available in José's Slideshare space.
Vowel Letter Pronunciation