Here is an article which will help not only the student, but you, the homeschooling parent/teacher. It will clarify some things for you as you teach phonics and spelling.
One thing I would like to add — over the years, English pronunciation has deteriorated significantly. Take a look at McGuffey’s Eclectic Spelling Book. There are seven pronunciations for the letter A. Today we only have three, but back in the nineteenth century, our language was much more precise.
Download your Pronounce for Spelling Technique to hang on your refrigerator.