Teachers feel forced to "manipulate results" amid increasing pressure to ensure pupils pass exams, a poll has suggested.
Many feel that their professionalism and integrity is at stake as school leaders, league tables, parents, Ofsted and politicians demand better grades.
After-school classes, one-to-one lessons, extra practice tests and rewards are all being employed by teachers to make sure their pupils pass, according to a survey by the Association of Teachers and Lecturers (ATL).
It found that almost three quarters (73.2%) of teachers feel under a lot of pressure to get pupils through tests and exams, with 70.6% saying this had increased in the past two years alone. Nearly two-thirds (63.9%) said they feel under more pressure now that 10 years ago.
There are fears that test pressure could affect teachers' professionalism, with almost two fifths (39.1%) saying it could be compromised. More than a third (35.2%) said their integrity could be compromised, the poll, published as ATL meet for their annual conference in Manchester, found.
The most popular way to help pupils to prepare for tests, outside of normal class work, was to supply more practice papers and questions than in previous years (cited by 71.2%).
Two fifths (41.5%) are helping pupils with coursework, while others lay on one-to-one tuition (63.2%), after-school classes (68.4%), weekend classes (9.1%) or offer rewards and incentives (25.7%). Around a third (31.2%) say they attend meetings to find out exam themes.
Teachers also raised concerns about the impact of exams on pupils, with most saying that testing is the biggest pressure on young people, ahead of other issues including bullying, family break-ups, financial problems at home and peer pressure.
ATL general secretary Dr Mary Bousted said the UK's children are still among the most tested in the world. This creates a huge pressure on young people, with many whose progress has been outstanding on a personal or emotional level feeling like failures following test and exam results," she said.
A Department for Education spokesman said: "There is absolutely no excuse for teachers cheating. Parents will be absolutely outraged to hear anyone admit they've manipulated test scores. It undermines other staff, damages children's education and risks destroying the public's faith in the profession."