In teaching language, errors of commission like those above are pretty common. Even more common, however, are errors of omission. If teachers simply omit any information about the morphological structure of words (often because they are unaware themselves), then students persist in approaching words as whole pieces, or as units analyzable by sound only. If teachers commit the error of omitting instruction in favor of memorization, then students will come to think of words and spelling as things to be memorized, rather than as things to be studied, investigated and understood.