Developmental milestones for high-schoolers

In high school, kids’ development really takes off. Just as with middle-schoolers, high-schoolers develop at widely varied rates. For the most part, tweens turn into high-schoolers who start looking more like adults while also building the skills to think about and plan for the future.

Physical milestones

The difference in growth between boys and girls is very noticeable at this age. And there’s a big difference in physical milestones among individual kids, too. Boys are hitting the age when they start to grow rapidly, while girls are just starting to slow down.

By the end of high school, many girls are likely to have grown as tall as they’re going to be. Boys, on the other hand, often are still growing and gaining muscle strength.

Many high-schoolers:

  • Have a big appetite

  • Need more sleep and may be sleepy in school

  • Have the visual-spatial coordination to judge distance and speed and react quickly when learning to drive

  • Are more agile and coordinated, making it easier to do things like type on a keyboard or build complex projects (Some teens may be uncoordinated, though, because they’re growing so quickly.)

Cognitive milestones

In the mid- to late-teenage years, kids start thinking not just about their own lives, but also more about how the whole world works. That change is a gradual process. It doesn’t happen all at once. During high school, teens are likely to:

  • Show an increasing ability to reason, make educated guesses, and sort fact from fiction

  • Start thinking more abstractly, comparing what is to what could be 

  • Think about and come up with ways to deal with hypothetical situations

  • Begin to set their own goals for the future; take other opinions into account but make their own decisions

  • Understand the consequences of actions, not just today, but also in far-reaching ways (For example, understanding that failing English isn’t just a bummer — it can mean summer school, too.)

  • Develop a strong sense of right and wrong and make decisions based on following their conscience

  • Write with complexity about a variety of content areas (science, social studies, literature)

  • Use strategies to search for, use, and compare information from multiple sources

  • Use numbers in real-life situations (like calculating tax or a tip)

Social and emotional milestones

There are huge changes in social and emotional skills between ages 14 and 18. The emotional maturity of a high school freshman is very different from that of a graduating senior. Here’s what you might see at different ages.


  • Can recognize personal strengths and challenges

  • Are embarrassed by family and parents

  • Strive to be independent

  • Are eager to be accepted by peers and to have friends

  • May seem self-centered, impulsive, or moody


  • Don’t want to talk as much; are argumentative

  • May appreciate siblings more than parents

  • Narrow down to a few close friends and may start dating

  • Analyze their own feelings and try to find the cause of them

16- to 18-year-olds

  • Start relating to family better; begin to see parents as real people

  • Develop a better sense of who they are and what positive things they can contribute to friendships and other relationships

  • Spend a lot of time with friends

  • Are able to voice emotions (both negative and positive) and try to find solutions to conflicts

From learning to drive to starting to think about the future, high school is a time of big change and growth. Learn about different paths to success kids can take after high school.

Key takeaways

  • High-schoolers hone their reasoning skills and learn to find solutions to problems.

  • By the end of high school, teens typically can appreciate the positive things about themselves.

  • Older teens can usually voice their emotions — negative and positive.


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