What is the best way to teach the vowel team , when 2 vowels go together not always work, and how to teach that sometimes 2 vowels say on sound and them 2 different voewls say the same sound.?
Thanks so much
This is extremely late, so you may not see it; but here goes.
You are right not to teach "2 vowels go walking and the first one does the talking because when students forget the sound of a diphthong, like /oi/, they will want to pronounce it as a long /o/ sound. In addition, there are v/v words like neon, and radio in which both vowels "talk"
The sequence that I use (which comes from Project Read/Language Circle) is:
These are the common, most frequently used sound/letter representations used. And they are taught just 2 or 3 at a time. Much later, after these have been mastered and are solid, then you can teach the least frequently used teams such as /ou/ in youth, group, and soup.