Schools should tell parents what sex education their child is being taught, the education secretary has said.
Gillian Keegan is encouraging schools in England to share what materials they are providing in the classroom to "debunk the copyright myth that parents cannot see what their children are being taught".
Ms Keegan has also written to parents to inform them of their right to know what their children are seeing and being taught in the classroom.
She said that companies providing teaching resources cannot use copyright law to forbid schools from sharing materials and that any attempt to do so through contract terms would be unenforceable and void.
Ms Keegan's letter to teachers and parents comes after a review into Relationships, Sex, Health and Education (RSHE) was announced in March amid concerns that children are being exposed to "inappropriate" content.
However, the guidance, which was supposed to come out in the summer, has yet to be published after the government said it would go out "for full public consultation later this year".
Schools are also waiting to receive separate guidance for transgender pupils but that has also been delayed due to legal concerns.
The Department for Education (DfE) is currently leading the review into RSHE education, which is also being informed by an independent panel to provide "external expertise".
The government has previously indicated the panel would advise on "clear safeguards to stop pupils from being taught contested and potentially damaging concepts", including bringing in age ratings setting out what is appropriate to be taught at what age.
Ahead of new guidance being published, Ms Keegan has written to teachers and parents to make it clear that companies providing teaching resources cannot use copyright law to forbid schools from sharing materials.
The education secretary said any attempt to do so through contract terms would be unenforceable and void.
"No ifs, no buts and no more excuses," she said.
"This government is acting to guarantee parents' fundamental right to know what their children are being taught in sex and relationship education."
She added: "Parents must be empowered to ask and schools should have the confidence to share."
Jason Elsom, chief executive of parenting charity Parentkind, welcomed what he called the government's "timely move to strengthen parental rights in the teaching of RSHE".
He said parents want transparency and the update "should help to reassure parents about the content and provision of RSHE".
Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), said the clarification over copyright was "helpful" but warned the letter could create an expectation on schools to publish "every piece of planning and resource used across the RSHE curriculum" which could lead to increased workload for teachers.
The school leaders' union the National Association of Head Teachers (NAHT) said the transgender guidance and the RSHE guidance are "what is really missing from this announcement".
The government launched its review into how sex education is taught in schools after a Conservative MP claimed pupils were being given "graphic lessons on oral sex, how to choke your partner safely and 72 genders" - something that was dismissed by the NAHT as "politically motivated".
Meanwhile, Sky News reported in July that the government delayed publishing its long-awaited transgender guidance for schools after its own legal advisors concluded some of the suggested elements would be unlawful.
Mr Sunak had promised to bring out the advice during the summer term but it is understood that three of the suggestions - including banning pupils from socially transitioning at school - would have been in breach of the Equalities Act.