The average age of first menstruation in the US is 12, though it is healthy to start menstruating between ages 8 and 15. Therefore, it is ideal to discuss this aspect of puberty before this time.
The good news it that by the time girls get their period, most have heard something about periods, sex, and babies. This is a good place to start your lesson: ask students what they have already heard about periods and make a list of student responses on the board.This allows you to correct misinformation and ensure they receive the facts.
Use the list generated by students as a jumping off point for discussing menstruation and the monthly cycle. The following learning objectives are adapted from the National Sexuality Education Standards.
- Describe the female reproductive system including body parts and their functions
- Explain how the timing of the first period varies considerably and can still be healthy.
- Describe how puberty prepares human bodies for the potential to reproduce.
- Identify parents or other trusted adults of whom students can ask questions about their period or turn to if something happens in school.
- Explain ways to manage the physical and emotional changes associated with the menstrual cycle.
- Identify medically-accurate information about female reproductive anatomy and puberty.
If a student, or her parent, wants additional information, these great books discuss both the first period and other changes during puberty:
- It’s Perfectly Normal by Robie Harris
- The Care and Keeping of You: The Body Book for Younger Girls by Valorie Schaefer (ages 8+)
- The Care and Keeping of You 2: The Body Book for Older Girls by Cara Natterson (ages 10+
The Office of Women’s Health maintains a stellar website for girls that are a great resource to refer to students and families. Girls’ Health includes information on all aspects of adolescence and puberty including getting one’s period. Kids Health also maintains a library of resources for both children and parents.
Changes, Changes, Changes: Great Methods for Puberty Education
Lesson plans on puberty
 McDowell, M. A., Brody, D. J., & Hughes, J. P. (2007). Has age at menarche changed? Results from the National Health and Nutrition Examination Survey (NHANES) 1999-2004. Journal of Adolescent Health, 40(3) 227-231.