Absolutely terriffic.  I have a grandchild having some difficulties with the sounds of letters.  I am going to send these to my son and daughter in law to see if they can use them to help.  As sad as it is…for some reason there was a period of times schools taught sight reading…recognizing words in their complete appearance rather than phonetics.  Now they are working their way back to phonetics but some parents can’t seem to teach it that way.  I hope this helps your son as much as I think it will my grandson, Kalen.