Short vowels are more common in English than long vowels. However, short vowels are often more challenging for multilingual learners because they are unfamiliar sounds. If a student speaks a Latin based language such as Spanish or French, I recommend beginning by teaching short vowels before long vowels because of the first language interference. Introducing one short vowel per week works well for older English learners. For younger students, a longer period is more appropriate.
If a teacher applies the principle of teaching from what is known to what is unknown, they would teach short vowels in a nontraditional order. Most English language teachers automatically begin with Short A and proceed alphabetically. However, there are two reasons why Short A should be taught last. First the American Short A sound is an uncommon sound among world languages. It is often difficult to hear and learn, so many English learners struggle to produce this odd sound. Secondly, many students who come to the U.S. have learned British English and use the British Short A. This interferes with learning the American Short A sound.
When teaching any new sound using visuals is extremely helpful. English learners often connect the sound with the object shown and this aids the learning process. Pictures combined with essential English words relevant to the students' lives, is a highly effective method of teaching all sounds. Vowels are more challenging because very few essential English words begin with vowels.
Once the vowel sound has been learned, teaching without visuals often helps students to focus more closely on the letter sounds. Some students are distracted by the pictures. Others use the picture to decode the word rather than actually blending the letter sounds.
Singing as another mode of teaching vowel sounds. The lyrics below are sung to the tune of 'Frere Jacques / Brother John'. This song is common in many countries.
A has two sounds; A has two sounds. /a/ and /A/, /a/ and /A.
/a/ /a/ /a/ - apple, /A/ /A/ /A/ - April. /a/ and /A/, /a/ and /A.
E has two sounds; E has two sounds. /e/ and /E/. /e/ and /E/.
/e/ /e/ /e/ - exercise. /E/ -/E/ /E/ - eleven. /e/ and /E/. /e/ and /E/.
I has two sounds; I has two sounds. /i/ and /I/. /i/ and /I/.
/i/ /i/ /i/ - inch, /I/ /I/ /I/ - ice. /i/ and /I/. /i/ and /I/.
O has two sounds; O has two sounds. /o/ and /O/. /o/ and /O/.
/o/ /o/ /o/ - on/off. /O/ /O/ /O/ - open. /o/ and /O/. /o/ and /O/.
U has two sounds; U has two sounds. /u/ and /U/. /u/ and /U/.
/u/ /u/ /u/ - up. /U/ /U/ /U/ - uniform. /u/ and /U/. /u/ and /U/.
As soon as students grasp short vowels, begin teaching words with closed syllables which contain short vowels.