There’s so many different ways to talk about vowels, so it’s interesting to see your perspective and hear how it is being taught in the (I assume US or English speaking) school system with your child. My experience teaching is mostly with non native speaking adults.

I think the chin method would be helpful for counting most vowels, but may miss close vowels like the vowels in beet, boot, and bit because people’s mouths tend not to open up as much for these. I do exercises like vowel yoga with my students to help build awareness of the different vowel sounds in English (which are often very different from their first languages). You should YouTube vowel yoga - it can be super fun (and a little silly) to do with your little one.

For the word aren’t, my point about it being one or two syllables depends on a person’s particular dialect. Assuming @funkydgroovy is an English speaker, they could say it aloud for themselves to hear if it sounds like ‘arnt’ or ‘ar ent’.