The letters "s", "ing", and "ed" are verb endings that change the tense or number of a verb. "S" is added to make a verb plural or indicate present tense (third person singular). "Ed" indicates past tense. "Ing" indicates a continuous or ongoing action. Phonics is a method of teaching reading that focuses on the relationship between sounds (phonemes) and letters (graphemes). It helps children decode, or sound out, words by understanding how letters represent sounds. This knowledge is crucial for both reading and spelling.