English is not a phonetic language. About half of our words are either spelled according to non-phonetic "rules" or follow no discernible pattern at all (they are historic spellings). To prepare children to succeed with this complicated language, we teach them not only the sounds of the single alphabetic letters (pink and blue sandpaper letters), but also the sounds of the most common phonograms (green sandpaper letters). And we teach all of these sounds at the same time! There is no need to wait to introduce phonogram sandpaper letters. They will be hearing those phonemes in language so why not give them the common symbol that matches what they are hearing?
Once children know most pink, blue, and green sandpaper letters, they are ready to start using the movable alphabets. After experience building words with those, they will start decoding words...reading. When this happens, we give them phonetic, predictable words to read so that their confidence grows (Levels 1 and 2 of our Phonetic Reading Cards). But very soon after (often within a week or two) they are ready to read words that include phonograms (Level 3 of our Phonetic Reading Cards, shown below).
Finally, we help them extend into accurately spelling words that contain phonograms via our Phonogram Reading Lists.