Short vowels are more common in English than long vowels. However, short vowels are often more challenging for English learners because they are often unfamiliar with these sounds. If a student is from a European language family such as Spanish or French, I recommend beginning by teaching short vowels before long vowels because of the first language interference. As an adult ESL instructor, I introduce one short vowel per week. For younger English learners, a longer period may be more appropriate.
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.
Singing as another mode of teaching short vowels. Below are the lyrics for teaching the long and short vowel sounds. They are sung to the tune of 'Are You Sleeping. Brother John?'
A has two sounds; A has two sounds. /A/ and /a/, /A/ and /a/.
/A/ as in April, /a/ as in apple. /A/ and /a/, /A/ and /a/.
E has two sounds; E has two sounds. /E/ and /e/, /E/ and /e/.
E as in eleven, e as in exit. /E/ and /e/, /E/ and /e/.
I has two sounds; I has two sounds. /I/ and /i/, /I/ and /i/.
I as in ice, i as in inch. /I/ and /i/, /I/ and /i/.
O has two sounds; O has two sounds. /O/ and /o/, /O/ and /o/.
O as in open, o as in on/off. /O/ and /o/, /O/ and /o/.
U has two sounds; U has two sounds. /U/ and /u/, /U/ and /u/.
U as in united, u as in up. /U/ and /u/, /U/ and /u/.
As soon as students grasp the short vowels, I recommend teaching closed syllables which end with a consonant/s and contain a short vowel. This is their next step to learning about syllables.