Ask anyone struggling with reading and/or spelling if they feel defeated by  "crazy English spelling" with words like "does" and "sign" that have to be memorized because they don't make sense. What if we could understand these spellings? It turns out we can.  The base "sign" spells the word "signal" when you add the suffix "-al" and "design" by adding the "de-" prefix. Why do schools and remedial programs ignore the fact that -- in English -- the pronunciation of morphemes (bases and affixes) can vary across related words, but use the same spelling to mark that meaning connection. The word "does" is totally logical. It has the structure "do + es" which parallels the structure "go + es". Instruction which can't explain such basic spellings is deficient. My research an practice is built on the obvious premise that literacy instruction should accurately represent our writing system. Google "structured word inquiry" if you are interested in understanding English spelling.