This document discusses principles of individual differences and types of differences people can have. It identifies physical, mental, emotional, psychomotor skills, achievement, interests and aptitudes, and learning differences as types of individual differences. Factors affecting differences include heredity and environment. The educational implications are that not all students are the same, teachers should understand students' abilities and needs, and one teaching method does not work for all given individual differences. Schools can help meet these differences by understanding students, ability grouping, adjusting curriculum and teaching methods.