Traditional GCSE coursework is to be scrapped for most academic subjects following a report by exam watchdogs.
There had been concern that some pupils may cheat with coursework
From 2009, it will be replaced by what is being called "controlled assessment", where pupils will do projects under supervision in class.
The changes come amid concerns about pupils cheating by copying from the internet or getting help from parents.
They will apply across England, Wales and Northern Ireland. Science coursework will not be affected.
This is because science GCSE courses changed last year and much of the coursework involved is already done in school.
The changes follow a review by the exams and curriculum body for England the QCA, working closely with counterparts in Wales and Northern Ireland.
They will affect nine subjects, including English literature, geography and history.
A QCA report, published last autumn said GSCE coursework had become "less valid".
Two-thirds of teachers surveyed for the study had said they did not think coursework was valid and reliable.
The QCA says pupils doing supervised projects in class may work on their own or in groups, but they will be monitored by a teacher and access to books, the internet and other sources of information will be controlled.
Consultation is taking place about what kind of supervision there should be for this work, ranging from direct to loose.
There will also be reforms to the way coursework is set and marked. Currently teachers in each school design the work and mark it, and outside moderators check samples of results across the country.
In future the exam boards will set the coursework as well as the exams. Teachers will continue to mark that work, but the regulators say once coursework is more streamlined, it will be easier to moderate effectively .
The head of England's QCA, Ken Boston, said: "The ability of the GCSE to stretch and challenge young people has been reinforced by the proposals that examinations must include extended writing and more varied question types.
"Controlled assessments will increase public confidence in the GCSE and allow the integration of new sources of data and information, including the internet, under supervision."
Problems of plagiarism
Head teachers say they are pleased that coursework will not be lost altogether and will remain in the form of extended work done in school.
John Dunford of the Association of School and College Leaders said: "Coursework has a major contribution to make to exam grades because it can be used to test a much wider variety of knowledge and skills than a written exam lasting a couple of hours."
"I am pleased that calls for coursework to be abolished have been headed off by this proposal for it to be done under more controlled conditions and for that reason I support it.
"The internet has changed the parameters of coursework and the continued credibility of coursework marks depends upon the work being done under more controlled conditions. It's important that we do not lose the positive side of coursework because of the problems of plagiarism".
John Bangs from the National Union of Teachers said cheating was not widespread but the issue did need looking at.
"A review of coursework was long overdue, for example the drawing down of information from the internet and parents helping, but outright cheating was rare.
"Proposals have come forward without being trialled and I worry about undermining the confidence of parents and children in their results this year."