Brain 
Parietal Lobe
Brain Stem
Cerebellum
Temporal Lobe
Frontal Lobe
Teenagers often have a difficult time remembering certain things. This could be that the temporal lobe is not fully matured. An example might be that they go to school and do their best to pay attention and listen but when the teacher tells them their homework they do not write it down in a place that will remind them to do it. It is often as if words have the tendency to go in one ear and out the other in adolescents.
A well developed temporal lobe might speak up and say "Hey! This is important, create a reminder in your phone or write it down so you don't forget" It could be as simple as remembering that your mom told you to fill up the car before you brought it back home.
Memory
The brain stem is responsible for keeping the body alive and well. It is the checks and balances of the functioning body. It must keep the heart beating, the body breathing, and making sure it is getting enough rest to function. Teenagers however tend to disrupt or interfere with the sleep aspect by staying up too late and not getting too much sleep or oversleeping to compensate. Too much of either is not healthy, as it throws off your body clock and can cause they body to function more poorly throughout the day.
A well aware teen does their best to make sure they get their 8-10 hours of sleep to keep their body growing and in proper health ("Students and sleep," 2019). This might mean setting an alarm to put your phone down one hour before they get in bed and set their phone across the room so they have to wake up and get out of bed to turn off their alarm in the morning.
Sleeping
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When teenagers experiment with alcohol under the age, they often get tipsy or drunk which leads to lowered inhibitions, poor judgment, and bad body coordination. This affects their balance to walk in a straight line or even touch their nose. This can be dangerous because they can be a harm to others.
Responsible adolescents who do drink, know their limit, and stop drinking before they become tipsy or drunk. They will look out for others who do decide to drink above their limit. And by making smart decisions, they are not contributing to the numerous accidents caused by drunk driving. As they get older they can also pay attention their own body posture trying to intentionally correct it so they don't have issues in their elderly years.
Balance & Posture
Teenagers are sometimes unaware of the importance of spatial relationships. This can show in driving, whether they are tailgating a car or staying too far back. they have a hard time understanding an appropriate distance. Leading to potential car accidents.
Adolescents who are aware of spacial relationships can better understand the importance of knowing where they are in relation to other and better protect themselves and those around them. Example: Instead of walking in a straight line through a crowded airport, they are aware of those around them and pass slow people and get out of fast people's way
Understanding spacial relationships
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Reasoning
Reasoning is using judgement to determine right or wrong. But this does not come easy to teenagers because they tend to act on impulse and not always weigh out the pros and cons before making a decision. A reason for this could be that the frontal lobe of the brain is not "fully developed until halfway through the third decade of life (Johnson, 2009)." Example: They could choose to act on impulse and skip school one day because they weren't feeling like it only to find out they missed a pop quiz.
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A fully developed frontal brain has the power to take a step back from a situation or decision and receive insight on what might happen based on the decision they choose. For example: You are invited to go to an amusement park with a friend but it means missing out an important meeting at work. Your fully formed frontal lobe would look at the benefits and cons of the situation: having a fun day vs. blowing off work, losing a possible chance of promotion in the future vs. rescheduling for a different day at the amusement park.
References:
Johnson, S. B., Blum, R. W., & Giedd, J. N. (2009). Adolescent maturity and the brain: the promise and pitfalls of neuroscience research in adolescent health policy. The Journal of adolescent health: official publication of the Society for Adolescent Medicine, 45(3), 216–221. https://doi.org/10.1016/j.jadohealth.2009.05.016
Students and sleep. (2019, February 21). Centers for Disease Control and Prevention. https://www.cdc.gov/features/students-sleep/index.html#:~:text=Importance%20of%20Sleep&text=The%20American%20Academy%20of%20Sleep,10%20hours%20per%2024%20hours