Examiners are monitoring exams for signs of cheating after the robbery of question papers from a delivery van.
Pupils are being told to focus on their revision
Sealed boxes containing papers for GCSE English literature, geography, German and Spanish were found in the street in Croydon on Friday.
The exam boards concerned - AQA and OCR - have decided not to change the exams but will watch for cheating.
The papers were stolen at knifepoint from a Parcelforce van in Mitcham, south London, on 19 April.
The driver of the van, which also contained pupils' coursework, was "very shaken" but unhurt, a spokeswoman for the Royal Mail said.
The Joint Council for Qualifications, which represents the exam boards in England, Wales and Northern Ireland, said AQA and OCR were "assessing the situation".
"In these circumstances, awarding bodies have tried and tested systems in place to ensure no candidate is unfairly disadvantaged," the council said in a statement.
"The chief examiners responsible for the relevant papers will identify any unusual trend or patterns in marks given to students in the areas involved.
"The awarding bodies also have available to them indications of past performance and will look for unusual trends or patterns.
"We will be alerting the three schools concerned and asking teachers to be extra vigilant.
"The most important message for students is to continue their revision and exam preparations as