GCSE pupils should be prevented from taking coursework home as part of efforts to stamp out cheating, the exams watchdog for England has advised.
There is concern over students' use of the internet
The Qualifications and Curriculum Authority warns that copying from the internet and help from parents pose "a threat to the fairness" of GCSEs.
Ensuring more work is done at school rather than at home will also reduce the burden on students, it adds.
The government is expected to comment on the proposals later in the year.
QCA chief executive Ken Boston said there were several problems with cheating in GCSEs.
For instance, pupils "creating a physical product" for arts or crafts subjects or carrying out lengthy investigations could get parental help or copy from websites.
In a letter written in April to the then education secretary, Ruth Kelly, but just published by the QCA, Dr Boston said: "We recognise that the practice of students carrying out coursework at home and the wider availability of the internet have created greater opportunities for malpractice.
"This gives problems with ensuring authenticity - the extent to which we can be confident that internally assessed [within schools] work is solely that of the candidate concerned.
"This is a threat to the fairness of GCSE."
However, Dr Boston said coursework completed at home could help develop "valuable life and work skills", warning that it was important to ensure "adequate exposure to those skills".
The QCA is expected to send a final list of proposals to the Department for Education and Skills (DfES) in the autumn.
Last year, a QCA report said many students were copying each others' work and downloading essays from the internet.
Some parents and teachers were effectively doing children's coursework for them, it added.
Commenting on the letter from the QCA, shadow minister for schools, Nick Gibb, said it was vital that confidence was retained in the exam system and welcomed QCA's plans.
He said: "There has been a huge problem with coursework as a means of assessment in recent years as plagiarism and illicit outside help has undermined the objectivity of the exam. It has added to the general concern about standards and the value of the GCSE as an exam."
A DfES spokesman said: "We have already announced that QCA have a remit to review GCSE coursework.
"The expectation is that in future it will only be used where it is the most valid way of assessing subject specific skills that cannot be assessed in a terminal exam."