In kindergarten or 1st grade, children who easily segment words or word parts (syllables) into their individual sounds have a strong start for reading.
Activity #1 teaches that sentences are made up of individual words.
Activity #2 teaches that words are made up of one or more parts (syllables). Some words have only one part (sun) and some have more than one part (sunset).
Activity #3 teaches that each part, or syllable, is made up of individual sounds (phonemes).