In the English language, there are 16 "key" phonograms:
ai, er, ie, ee, or, ue, oo, qu, th, ch, oy, sh, ou, oa, ar, au
All others are variations on these ;)
|The sandpaper letter phonograms|
The sandpaper letters phonograms should be introduced at the same time as the individual sandpaper letters - learn 3-5 individuals, then introduce a phonogram; continue introducing one new one at a time with individuals in between such that all sandpaper letters, individual and phonogram, are finished up at about the same time - typically 3 weeks after beginning the first sandpaper letters ;)
In this way, the children can immediately write anything with the movable alphabet, without needing prompts or guides as to what they can write versus what they have not yet learned - they'll have learned it all!