The education secretary has promised to cut teachers' workload in an attempt to resolve a recruitment crisis in England's schools.
Damian Hinds told a head teachers' conference in Birmingham that there will be no more new changes to primary tests, GCSEs or A-levels.
But he faced challenges from delegates over school funding shortages.
And Mr Hinds told head teachers: "It has been tough, funding is tight, I don't deny that at all."
Geoff Barton, general secretary of the Association of School and College Leaders, welcomed the education secretary's promise to cut the "bureaucratic burden" on teachers.
But there were calls from the conference floor for Mr Hinds to "answer the question" over problems with school funding.
The education secretary had conceded: "I understand why that's people's number one issue. I understand why, for everyone in this room, the funding of our schools and colleges is such an important topic."
In his first speech to heads and teachers since becoming education secretary, Mr Hinds said that tackling the teacher shortage was a "top priority".
Mr Hinds said long hours and red tape were among the "biggest threats" to recruiting and retaining staff.
For five successive years, recruitment targets for teaching have been missed and schools have complained of the expense and disruption of relying on temporary staff or having to use teachers who are not specialists in the subjects they are teaching.
Schools are spending £835m per year on supply agencies, according to the most recent government figures.
Freeze on exam changes
The education secretary told the head teachers' conference on Saturday: "With rising pupil numbers, I recognise that recruitment and retention is difficult for schools.
"And, clearly, one of the biggest threats to retention, and also to recruitment, is workload.
"Too many of our teachers and our school leaders are working too long hours - and on non-teaching tasks that are not helping children to learn."
Mr Hinds promised head teachers no more changes to the curriculum or to testing and exams in primary or secondary school until the end of this Parliament.
But existing reforms that are already in the pipeline, such as the roll-out of changes to GCSEs, will go ahead.
Mr Hinds spoke alongside the Ofsted chief, Amanda Spielman, and they highlighted the need to avoid any unnecessary bureaucracy around inspections.
Ms Spielman said that Ofsted wants to help to reduce workload.
Improvements in school will not be sustained "if the people, who make them run so well, are burning out and leaving the profession", Ms Spielman told the head teachers' conference.
She warned against "entirely unnecessary" extra work such as rehearsals for inspections, so-called "mocksteds".
Mr Barton, ASCL's general secretary, supported the push to cut workload.
The heads' union has warned repeatedly of the recruitment problems facing schools, particularly in maths and science.
The heads' leader warned that the ways into teaching have become confusingly complicated and need to be simplified.
But Mr Barton said head teachers should work differently to reduce workload in their own schools, such as cutting needless meetings or administration.
"In the longer term, we're the generation who needs to redefine what it is to be a teacher in the 21st Century, to make sure we don't become the Luddite profession, doing things in the way we've always done them."
Labour's shadow schools minister, Mike Kane, said: "This government can't offer a solution to the crisis in teacher recruitment and retention because they created it.
"If the government were serious about ending the crisis in teacher recruitment and retention they would match Labour's fully-funded commitment to scrap the public sector pay cap and give our teachers the pay rise they deserve."