An underachiever is a learner whose achievement consistently falls below their potential ability. There are two types of underachievers: situational underachievers, whose underachievement is temporary, and chronic underachievers, whose underachievement persists. Characteristics of underachievers include being disruptive or quiet in class, having poor attendance and low self-esteem, and lacking motivation or goals, while causes can be physical, social, family-related, or school-related. Remedial measures include early identification and counseling, special classrooms, adjusting activities, improving home-school interaction, and addressing underlying causes of underachievement.