Type: Activity / Contextual
Description: Instruction, often practical, relating to puberty, reproduction, and sexuality in general.

Notes: This includes in class lessons with or without practical components, as well as more private sessions in or out of school. The 'teacher' must actually teach about sexuality, or explain aspects of, or the development of, the body like the genitals and secondary sexual characteristics.

Japanese: 性教育

In class examples:
http://ehentaihip.com/g/977406/4ed0ff32c7/
http://ehentaihip.com/g/855910/c339e5c670/
http://ehentaihip.com/g/296605/ff718d477c/
http://ehentaihip.com/g/1263139/783dba0cec/

Outside of class example:
http://ehentaihip.com/g/2283250/3c5bb79e73/

Outside of school example
http://ehentaihip.com/g/572883/d6554896c2/


I suggest this tag because although it is relatively common, it is often hard to find this type of content using existing tags.