The amendments were devised by opposition Harmony party deputy Julia Stepanenko, who won the vote by 64 votes to 12 with at least some members of 5 out of the 6 parties in Saeima supporting her.
"The amendments provide for an obligation for schools to provide students with moral education, which corresponds to those contained in the Constitution and protected values, especially such as marriage and the family," said the Saeima press sevice.
"Members today also supported the proposal stating that learners are protected from such information and methods of education and upbringing, which do not correspond to the purpose of the student moral development."
That seems to indicate that students will be taught morality but not immorality or amorality.
The amendments also introduce rules on teaching how the national anthem and national flag should be treated in schools.
At the end of April after extensive debate, the Saeima supported some of Stepanenko's less radical proposals but disposed of others of a more overtly censorious nature.