The English language has rules that we must follow to spell words correctly. In reality about 85% of the English language is phonetically reliable for spelling. It is up to us as educators to explicitly explain and model these rules. The Doubling Rule The Doubling Rule When adding a vowel suffix to a one syllable base word ending in a short vowel and one consonant, you must double the final consonant before adding the vowel suffix. Click here, if you would like a free printable of the Doubling Rule .