This document discusses different theories of intelligence and definitions of intelligence quotient (IQ). It provides classifications of intelligence levels from genius to idiot based on IQ scores. It also profiles Alfred Binet, who developed one of the first IQ tests to identify students needing extra help in school. Binet defined intelligence as the capacity to judge, reason, and comprehend well. The document also summarizes Binet's single factor theory of intelligence, which views intelligence as a general ability affecting all individual activities. However, this theory was later criticized by Charles Spearman who argued intelligence is a combination of general and specific factors.