Advanced Book #7 "Ow Vowels" was just posted.
This book tackles the "Ow" vowels --
- ow/ou (such as in how, cow, about, etc.)
- aw/au (such as in draw, sauce, because, etc.)
- ew (such as in new, flew, etc.)
It also tackles the various words that are spelled the same, but pronounced differently (snow, touch, soup, etc.)
These vowels are technically diphthongs, although some call them digraphs, but I call them the "Ow" vowels -- simple, easy, descriptive. (We're not analyzing the language here, we're just teaching kids to read for goodness sake!)