"O boy, you are growing taller", a middle-aged woman tells a boy, adding: "Now pull down your pants, and lemme see if your member is growing too?"

This picture with the speech bubbles from a sex education textbook for Grade 2 pupils, was posted by a child's mother on a social media website on Feb 28 to show how "inappropriate" the book was for children. And not surprisingly, it sparked fierce online discussions with many saying the book contains material not suitable for young children.

This prompted the book's editors to post online the full picture from the book which advises children facing such a situation to immediately leave the place, avoid such people in the future and inform their parents of the incident. Still, some micro-bloggers, including Li Tiegen, a commentator, continued their tirade against the book and the boy's school in Hangzhou, East China's Zhejiang province.

The school argues the textbook is part of a "book-crossing" collection put together by some people for free exchange. The boy acquired the book from that collection. Yet under tremendous pressure from social media, the school eventually had to withdraw the book from the collection.

The critics said the book contained pictures of and texts on sexual organs, meaning any book that contains such pictures are "unsuitable" for young children.

The problem is, books cannot provide even the basic sex education for children without pictures of and texts on sexual organs.

Children do not live in a vacuum today; they get some type of sex-related information from the internet, TV programs and/or movies. Enter the word "painless" in the input box of domestic online search giant baidu.com, and automatically the word "abortion" is added to it and a full screen of commercial advertisements with pictures covers the screen.

In the real world, the walls of many public toilets are full of ads with obscene pictures offering cure for venereal diseases.

It is better to educate our children about sex than to pretend ignorance about it, because the more we try to hide reality from our children the more interested they will be to know about it, which could even land them in danger.

Li and several other influential micro-bloggers have joked about the picture in the textbook, saying it is a pornographic tale about a middle-aged woman and a boy. Some have even implied that the boy should "enjoy" the sex.

Are they pretending to not know that even underage boys fall victim to sexual abuse, and sexual abuse is a serious crime?

The sex education book that many have ridiculed is part of a series of books published by Beijing Normal University after strict review by experts. It not only provides pupils with the basic information about sex and sexual organs, but also teaches children how to protect themselves against sexual abuse.

In 2013, some pictures from a German sex education textbook, Where Do Children Come From?, were posted on some Chinese websites. They drew applauses from internet users because they contained direct information about sex and genitals. Shouldn't we welcome Chinese books on sex education with a similar approach?

The author is a writer with China Daily. zhangzhouxiang@chinadaily.com.cn