The sound is what count (s).I teach the alphabet as names.  My name is , your name is, its name is  �A �  �B �  �C � etc.
And what sound do they make?  �B � says buh and so on.
Vowels are trickier as they even sound the same.  
But in this day and age my ss they know txt messaging.
So i �ve used abreviations as  �IOU � and  �urgr8 � to explain the vowel sound.
 
The ss have to translate.  After all, writing is like texting.  You only use all the letters :-)
The  �U � is like  �You � and as such not a vowel-sound.
Don �t forget the  �O � as in one.  Sounds like??? Indeed,  �W �. So it �s "a one dollar coin."
The silent  �H � is similar, but there are not many words starting with silent  �H �.  Hour, heir, honest, honour (honor) are the best known.
Cheers.
Peter