In 1956, Benjamin Bloom and a group of educational psychologists developed a classification of levels of intellectual behavior important in learning. In the 1990’s Lorin Anderson (a former student of Bloom) and a new group of cognitive psychologists updated the taxonomy to reflect relevance to 21st century skills. The new taxonomy is much more useful in language instruction.
Even more applicable to language learning and teaching is this graphic representation of the Bloom levels that demonstrates how these skills are not a hierarchy, but are interrelated and dependent on each other to function most efficiently and effectively. It shows that creating language is dependent on understanding and so forth.