If there's one subject that is guaranteed to ignite a storm of controversy in education, it's how and when to teach young people about sex. Japan and the United States serve as case studies.

In what can be called at best an embarrassment, the education ministry oversaw the distribution of material to high school students in a health class incorrectly stating that 22 is the peak age for women to bear children.

The false information undermined student confidence in their teachers, who had little choice but to follow orders.