Key checklist for this stage
- Check in Korea's immunization registry for the Tdap (or Td) booster at 11–12, Japanese encephalitis at 12 (5th dose if on the inactivated vaccine), and HPV for girls at 12.
- Talk about periods and wet dreams early and accurately, and get the supplies ready.
- Reset screen rules at bedtime to protect 9–12 hours of sleep.
- Ask for help if mood changes last more than two weeks or daily life falls apart.
- Strengthen daily rhythms and self-management habits before middle school.
Body changes — puberty
Girls: after breast development comes a growth spurt, and the first period usually arrives about 2–3 years after breasts begin to develop. Irregular cycles are common for the first year or two. Teach how to use pads and what to do if a period starts at school, and have them keep one in their bag.
Boys: the testes and penis grow, pubic and underarm hair appear, the voice changes and height shoots up. Explain in advance that wet dreams — releasing semen during sleep — are natural. Slight, temporary breast swelling can happen and usually goes away on its own.
Both: acne, sweat and body odor increase, and washing skin and hair daily becomes important. The timing and pace of puberty vary greatly; when your child compares themselves with friends and worries, tell them everyone has their own timing.
Feelings and talking together
Bigger mood swings, wanting to be alone and valuing friends' opinions over parents' are natural parts of puberty. Even a child who closes the door still needs parents' interest and consistent rules.
Conversations open more easily when they're short and side by side — in the car or on a walk — rather than face to face. Listen to their views fully, and set rules together while explaining the reasons.
Worries about appearance and weight grow now. Avoid teasing about body shape or diet talk, and make regular meals and exercise a family habit.
Friends and online safety
- Agree not to send photos or personal information to people met on social media or games, and to tell a parent if someone asks to meet.
- Repeat that if anyone asks for photos or makes threats, it's not your child's fault, and they can tell you right away without hiding it.
- Exclusion and insults in group chats are bullying. Save the evidence; in Korea you can get advice from the 117 hotline.
- Keep phones out of the bedroom and charge them in the living room.
Vaccines, sleep and activity
At 11–12 there's a Tdap (or Td) booster, and children who have received the inactivated Japanese encephalitis vaccine get their last dose at 12. In Korea, girls aged 12 receive two doses of HPV (human papillomavirus) vaccine through the national program. Eligibility and schedules can change, so check the immunization registry. A flu shot is recommended every year.
In puberty the body clock shifts later and children want to stay up. Still, 9–12 hours of sleep is recommended through age 12, so keep screens off an hour before bed and wake up at a regular time.
WHO recommends an average of at least 60 minutes a day of active play and muscle- and bone-strengthening activity at least 3 days a week. Sticking with one sport they enjoy also supports mental health.
Getting ready for middle school
Middle school brings subject teachers, exams and longer days. Gradually handing over self-management during the upper elementary years — managing their own schedule, asking questions when they don't understand, handling pocket money — makes the transition smoother.
Talk of grades and future paths increases, but enough sleep, downtime and family conversation are the foundation to protect before academics.
Vaccines & checkups in this stage
Korea's Childhood Vaccine Schedule → Infant and Child Health Checkups →
FAQ
At what age do girls usually get their first period?
It varies, but the first period usually comes 2–3 years after breast development begins. Many girls start in the upper elementary years, so talk about it and prepare supplies beforehand. See a doctor if there's no breast development by 13 or no period by 15.
Do boys get the HPV vaccine too?
In Korea, girls aged 12 are eligible for the national HPV vaccination (2 doses). Boys can be vaccinated after consulting a clinic; check the KDCA immunization registry for any expansion of national support.
I can't talk with my preteen.
That's common at this age. Make frequent, short times to listen without judging, and use relaxed settings like car rides or walks. Setting rules together, with reasons, reduces pushback.
My child seems depressed — is it just puberty?
Mood swings are common, but if it lasts more than two weeks or sleep, eating or school life falls apart, don't write it off as puberty. Consult a pediatrician or child psychiatrist, and in an emergency in Korea call 109 or 119.
Sources
- KDCA immunization registry
- Korean Pediatric Society
- Korean Society of Pediatric Endocrinology
- AAP HealthyChildren.org
- WHO guidelines on physical activity and sedentary behaviour
- Ministry of Health and Welfare suicide prevention line 109 (Korea)
Medical information is for reference only. This is general information and does not replace diagnosis or treatment. Always talk to your child's doctor. In an emergency in Korea, call 119.
Related
Independence and the weight of friendships grow. Some children begin showing the first signs of puberty. It's also a good time to set rules for a first smartphone.
Korea's Childhood Vaccine ScheduleIn Korea, national vaccines are free at public health centers and designated clinics. Plan ahead using the standard schedule, and check exact dates and your child's record on the KDCA Immunization Helper.
Media and screen timeThe younger the child, the more they need human interaction, active play and sleep rather than screens. Instead of banning screens perfectly, aim for age-appropriate limits and family rules so media is used well and in moderation.
Discipline and emotion coachingThe goal of discipline is to help children build the ability to manage their own behavior. With clear, consistent limits on a foundation of warmth, children learn without being hit or frightened.
Developmental checks and delaysEvery child develops at their own pace, but when you are worried about a delay, checking is better than waiting. Finding out early and helping early does the most for your child.
Sleep and safe sleepWith baby sleep, how safely comes before how long. Set up a safe sleep space first, then support sleep with age-appropriate expectations and a steady routine.