Vowel rules

Since I teach English (ESL/EFL), I need to help the students with pronunciation. I have to do a lot of research in this area in order to teach it effectively, and so far I've found some good sites.

One site is called called the Sounds of English, and it has some helpful information, especially about teaching vowel sounds.

According to the site, there are "two crude rules for decoding. They don't work for all words, of course, but often enough to be helpful for beginners..."

Here are the two rules and some examples:

The Two vowel rule: If there are 2 vowel letters in a short word (syllable), the first vowel sounds like its "alphabet name". These rules work for monosyllabic words or stressed syllables of multisyllabic words.

cake
remain
tea
repeat
ice
arrive
cone
soapy
juice
excuse

The One vowel rule: If there is only 1 vowel letter in a short word (syllable), it sounds like a "relative" of the alphabet vowel.
 
had
thank
bed
pencil
his
listen
hot
comic
sun
summer

Those rules are for beginning learners, but they were helpful even with intermediate students.