Invented spelling is "an attempt by beginning writers to spell a word when the standard spelling is unknown"; it involves using "whatever knowledge of sounds or visual patterns the writer has," notes Bank Street College (1997).
Burns, Griffin, and Snow (1999) point out the value of invented spelling in allowing young children to express their thoughts in writing:
"It is important for parents and teachers to understand that invented spelling is not in conflict with correct spelling. On the contrary, it plays an important role in helping children learn how to write. When children use invented spelling, they are in fact exercising their growing knowledge of phonemes, the letters of the alphabet, and their confidence in the alphabetic principle. A child's 'iz' for the conventional 'is' can be celebrated as quite a breakthrough! It is the kind of error that shows you that the child is thinking independently and quite analytically about the sounds of words and the logic of spelling." (p. 102)