The British government seems to have decided that four is the right age for children start learning about sex.
Ministers are tipped to roll out a new sex education scheme with a strong focus on consent and the dangers of sexting - and the classes will be compulsory.
The move was prompted by concerns children are learning about sex via the internet and online pornography.
Sex education is currently only compulsory at schools run by local authorities - excluding academies, independents and religious schools.
Lessons would be age-appropriate and would focus on issues including staying safe online, sexting and abusive relationships.
"There is a threat online and that threat we would all recognise has grown," a spokesman for 10 Downing Street says.
"That does mean that now is the right time to look at how we can ensure children have the access they need to the teaching in those subjects."