Build the word one letter at a time.
Word Builder shows a picture and asks the child to spell what it is, either by tapping letters in order or by filling in the one letter that is missing. Spelling by construction rather than by multiple choice means the child has to hold the whole word in mind, which is the part that transfers to writing.
The 8-10 level is almost entirely word building, using a longer word list and smaller tiles that fit more letters on screen at once.