Gardner identified eight types of intelligence: linguistic, logical-mathematical, spatial, bodily-kinesthetic, musical, interpersonal, intrapersonal, and naturalist. He argued that these intelligences are distinct from one another and that each person possesses varying levels of each. His theory challenged the assumption that intelligence is a single ability and that learning is a universal process, instead arguing that there are multiple intelligences. The MI theory requires teachers to develop varied instructional materials and strategies to address students' different intelligences.