What type of error is shown when a child spells "two" as "too"?

When a child spells "two" as "too," the error made is best categorized as an orthographic error. This type of error occurs when there is a mistake in the spelling of a word, regardless of the sounds or meanings involved. "Two" and "too" are homophones; they sound the same but have different meanings and spellings.

In this case, the child has confused the spelling of the word while retaining the correct phonetic sounds in their mind. Orthographic errors highlight the child's understanding of letter patterns and spelling conventions, which can differ from their phonological understanding of the sounds of words.

Phonetic errors involve more direct confusion regarding sounds and their correlating letters, but in this scenario, the child demonstrates awareness of phonemes while misapplying the orthographic rules of English. Morphemic errors pertain to mistakes made regarding the structure and meaning of word parts, and semantic errors involve misunderstanding a word's meaning or usage in context, neither of which applies here.