One of the students, speaking to newspaper The Tab, said:
"I raised my hand briefly, hoping to inform the invigilators of the error, but quickly retracted it after realising I might be the only one with the mark scheme."
On looking around, I heard one of my peers sniggering at the front of the exam hall, and then seconds later the whole hall was in stitches as our examiners looked on blankly. Surely the best start to any of my exams."
A red-faced convenor decided to remove the mark schemes from the test and give it back to students, hoping that they would not be able to remember most of the answers.
Students at a top university burst out laughing in the middle of an exam when they realised the answers were stapled to their test papers.
The first year exam turned into a shambles after a printing error resulted in the paper's mark scheme being attached to the back of the questions booklet.
It gave first year students the answers to the complicated test for 40 Electrical and Information Engineering pupils at Imperial College, London.
A number of the UK's leading universities are sliding down international rankings, jeopardising their reputations as some of the best places in the world to study for a degree, according to research.
The UK has 10 entrants in the Times Higher World Reputation Rankings this year, up one from 2013, but down from three years ago when there were 12 in the top 100.
Besides Oxford and Cambridge, these were Imperial College London (13th), the London School of Economics (24th), University College London (25th) and King's College London (43rd), as well as the London Business School and the London School of Hygiene and Tropical Medicine.
Scientists at Imperial Collegeare testing a new therapy to stop prostate cancer advancing to a deadly stage.
The team is developing "designer" proteins that could help patients once other methods have failed.
Each year around 37,000 men in the UK develop prostate cancer and 11,000 will die from the disease.
Engineering students from Imperial College have teamed up with the paralympic silver medalist Jon-Allan Butterworth to try and increase his chances of winning at gold medal in Rio.
The second year students hope the finished product will be ready for the paracycling world championships in 2014.
Luke Hanrahan went to meet them.
A new, more natural IVF treatment offering hope for women at risk of life-threatening complications from traditional fertility treatments has been pioneered at London's Hammersmith Hospital.
The study, conducted in conjunction with Imperial College London, tested the use of a naturally occurring hormone, kisspeptin, to induce egg development.
This allows women to avoid the use of traditional IVF drugs which can trigger a serious condition called ovarian hyperstimulation syndrome.
The women most at risk are those with polycystic ovary syndrome.
The study proved that kisspeptin can be successfully used in IVF treatment, with the first baby, a healthy boy, being born in April.