This news report from India shows one way to make it almost impossible to cheat on an exam.
It seems the precautions were necessary. The Guardian reports:
A year ago police in Bihar said they had arrested about 1,000 aspiring officers for paying people to sit their exams for them.
. . .
There is huge pressure in India to secure good school grades and highly sought-after government jobs. Methods of cheating uncovered range from old-fashioned crib sheets to hi-tech spy cameras.
Last year in another scandal in Bihar, relatives scaled the walls of a school exam centre to pass notes to candidates.
In another attempt to stamp out cheating, on Sunday authorities in the western state of Gujarat blocked mobile phone internet services in cities and towns where entrance exams were taking place for public service jobs.
There's more at the link, including a video clip of the incident reported above where 'relatives scaled the walls ... to pass notes to candidates'.
It looks like the Indian Army certainly tried to find a solution to the problem; but even so, why make the candidates sit and write on the grass? Surely, with all the resources of the military and local schools, tables and chairs could have been provided?