Puberty refers to the set of biological changes involved in reaching physical and sexual maturity and is universal. Adolescence refers to a life stage between the time puberty begins and the time adult status is approached. This is typically between the age of 10 to 18. In this stage, young people are preparing to take on the roles and responsibilities of adulthood in their culture. It is culturally constructed. The length (1), content (2) and daily experiences of adolescence (3) differ among cultures.

Plato and Aristotle believed that people develop reason in adolescence. In the middle ages, adolescence was seen as a time of innocence. Life-cycle service refers to a period late adolescence and early 20s in which young people would engage in domestic service, farm service or apprenticeships in various trades and crafts. This involved moving out of the family household and into the household of a master to whom the young person was in service for. This occurred between 1500 and 1890.

The period between 1890 and 1920 is known as the Age of adolescence as there were laws restricting child labour (1), requirements for children to attend secondary school (2) and the development of the field of adolescence as an area of scientific study (3).

The theory of recapitulation holds that the development of each individual recapitulates or re-enacts the evolutionary development of the human species as a whole. Adolescence was seen as reflecting a time of evolutionary turmoil and this was used as an explanation why adolescence is characterized by storm and stress.

The idea of storm and stress holds that adolescence is characterized by a period of upheaval and disruption. This is reflected in high rates of conflicts with parents (1), mood disruptions (2) and risk behaviour (3). Adolescence is a period which is not necessarily characterized by storm and stress although it is more likely in this period.

Emerging adulthood refers to the period of life between adolescence and full-adult status. This includes the ages between 18 and 25. This period has five characteristics:

1. Identity exploration.
2. Instability (e.g. moving a lot).
3. Self-focus.
4. Feeling in-between.
5. Feelings of possibilities and optimism.

People in this stage explore various possibilities in love and work and move towards making enduring choices. They develop a more definitive identity through trying out these possibilities. Emerging adults focus on themselves to develop knowledge, skills and self-understanding needed for adult life. The focus on the self does not mean selfishness.

Emerging adulthood does not exist in all cultures and cultures vary widely in the ages that young people are expected to enter full adulthood and take on adult responsibilities.

Self-conception refers to the notion of what kind of person one is. Self-esteem refers to the capacity to evaluate one’s fundamental worth as a person. Identity refers to one’s perception of their capacity and characteristics and how this fit into the opportunities available to them. Self-reflection increases in adolescence as a result of normal cognitive development but culture has a profound influence on how people experience this change.

People’s self-conceptions change with age. Self-conceptions become more abstract and more complex in adolescence. Self-conceptions become more trait-focused and the traits become more abstract (e.g. being outgoing).

There is a cultural difference between collectivistic (i.e. interdependent self) and individualistic (i.e. independent self) cultures with regard to self-conception. In collectivistic cultures, the self is defined by social relationships.

The ideal self refers to the person the adolescent would like to be. The feared self refers to the person the adolescent imagines it is possible to become but dreads becoming. Possible selves only exist as abstractions. The discrepancy between the ideal and the actual self can lead to problems (e.g. feelings of depression). However, awareness of actual and possible selves can also provide adolescents with motivation to strive toward their ideal self. Delinquent adolescents were less likely to have a clear ideal self. The false self refers to a self that adolescents present to others while realizing that it does not represent what they are actually thinking and feeling.

Adolescents need to learn how to understand and manage their emotions, though adolescence is characterized by heightened emotions. Brain development may lead to adolescents’ emotionality. There is low activity in the frontal lobes and high activity in the amygdala during emotional processing while the opposite is true for adults. Adolescents’ new and increased capacity for abstract thought as well as interpretation of new peer situations leads to a differential emotional response. Adolescents report less positive emotions compared to childhood.

According to Gilligan, boys learn to assert their opinions during adolescence while girls become insecure and lose their ‘voice’. This is the result of differences in emotional responses to social relationships with girls being more sensitive to nuance. The discrepancy between the desires of the culture for both sexes can lead to this and in its extreme, lead to heightened psychopathology rates. However, the studies are methodologically weak and self-esteem declines for both girls and boys in adolescence.

Adolescents are able to engage in frequent self-reflection because they are often by themselves. While their mood tends to be lower when they are alone (e.g. in their bedroom), their mood tends to rise after a period of being alone. This time may thus be used for self-reflection and mood management. Being alone can be constructive as long as the adolescent is not alone too often.

Social loneliness refers to the perception of lacking a sufficient number of social contacts and relationships. Emotional loneliness refers to the perception of lacking closeness and

Adolescents’ academic performance is related in crucial ways to their family relationships (1), friendships (2), work patterns (3) and leisure patterns (4). Cultural beliefs are important in determining what is required from adolescents academically.

Adolescents in developed countries started going to secondary school about a century ago. Schooling became the normative experience for adolescence. The same pattern is observed in developing countries but at a delayed rate. Adolescents being in school is a direct consequence of economic development.

The content of secondary school has changed over time as well. There was no specific economic purpose of the curriculum in the 19th century but this changed as more adolescents started attending school. Schools started to focus more on training for work and citizenship. The comprehensive high school includes classes in general education, college preparation and vocational training. Many European countries have three types of secondary schools:

• College-preparatory school
  This school offers a variety of academic courses and the goal is general education. It does not include classes on recreational subjects.
• Vocational school
  This school prepares adolescents for a specific occupation.
• Professional school
  This school prepares adolescents for a specific purpose (e.g. teacher training; arts).

In this European system, adolescents need to decide relatively early what kind of future they envision. A later choice is likely more beneficial for adolescents. However, putting adolescents with different interests and educational levels together makes it more difficult for teachers to provide effective teaching. It can also be frustrating for adolescents who do have a specific idea of their future.

Rates of secondary school enrolment vary widely among developing countries. The economy is often not industrialized which makes school-based knowledge of limited use. In China and Japan, admission to university is restricted to the highest performing students. This leads to intense pressure at high school level. Secondary education in developing countries is often characterized by gender differences (1), poor funding (2), overcrowding (3), poorly trained teachers (4) and a big difference between public and private schools (5).

The goal of schools used to be socialization and conforming to the (religious) norm. Nowadays, the goal is to promote independent thinking. In developed countries, almost all adolescents go to secondary school while this is not the case for developing countries. Tertiary education is obtained by about 70% of the emerging adults in developed countries but not in developing countries.

The key influence on adolescents’ academic performance is the level of economic development in their country. This means that the developed countries tend to perform best.

Large schools can be alienating but can also offer a more diverse range of classes. There is no consistent relationship between school size and academic achievement. Students in smaller schools are more likely to participate in extracurricular activities compared to students in larger schools. The best school size for adolescents is between 500 and 1000 students. The class size should typically be