Jerome Bruner proposed three stages of cognitive development: the enactive stage from birth to 3 years where learning is through movement and action; the iconic stage from 3 to 8 years where learning is through images and icons; and the symbolic stage from 8 years onward where abstract symbols are used to learn. Bruner's theory emphasizes that education should start with motor activities and teachers should select activities appropriate for the developmental stage of their students. It also supports using a spiral curriculum where concepts are revisited at higher levels of complexity.