The National Education Union has called for lessons about LGBT+ relationships to be compulsory in all schools.
At their annual conference in Liverpool today, the group voted in favour of campaigning to strengthen government guidance on sex and relationships education by forcing primary and secondary schools to teach LGBT+ lessons.
Under current guidance, secondary schools are expected to include LGBT+ content, while primary schools are enabled to cover LGBT+ content only if they consider it age appropriate to do so.
The move follows parental backlash to the No Outsiders programme at Parkfield Community School in Birmingham, which promoted LGBT+ equality to pupils.
Mary Bousted, joint general secretary of the NEU, said: "We can't address LGBT+ teenagers' self-harm and exclusion rates without talking openly and positively about LGBT+ people and their contributions to society now, and throughout history
"Silence about LGBT+ people is the wrong approach, and fuels homophobic bullying, inequality for LGBT+ workers and hate crime."
She added: "Schools need to be confident that they're right to make sure their relationships and sex education education is inclusive of all families and relationships, including LGBT+ people, in an age-appropriate way."