A teenager is easily bored in school, disengaging from the present moment and withdrawing either into their own mind, disruptive talk amongst peers, or to online distractions. But boredom should not be only looked at as a form of rebellion, though it may be that. It is also fundamentally a form of loneliness; from the world, from one's peers and from one's self.
Teens are more susceptible to boredom
Teachers should take into account the teenager's susceptibility to boredom. Perhaps find alternatives to teaching other than hour long lectures. Every subject can be engaging to adolescent students with a little bit of creativity on the part of the educator.
Priorities change for students as they change from children to adolescents. In childhood, performance, friendships and personal appearance are ranked in that order. Due to changes in brain development, adolescence reverses those priorities. Teachers must take this into account before getting frustrated or even offended.
Teen brains have a lot of plasticity, meaning that there is plenty of room for growth and adaptation
Teachers should never take the adolescent's ability to grow and adapt for granted. Very important brain connections are still being forged until at least a person's early 20's.
For pre-adolescent children, learning is satisfying and fun. For the teenager, learning makes one vulnerable. For example, peers may make fun of a student for asking a question or not getting something right.
Teachers should make sure to always promote a safe environment of learning, reinforcing respectful and cooperative behavior.
Teens don't live in just one world, but two. The parallel universe of online games and social media can make for a constant stream of social stress and anxiety. Toxic behaviors can be festering in the collective student online social habitat without teachers or parents knowing. Getting students to interface meaningfully with something other than the internet is an important part of their development. Teaching using computers should only be used some of the time.