Word for cheating off of another person's test in class

Given the Holiday Season, I would throw in:

cribbing (informal) - copy (another person's work) illicitly or without acknowledgment.

For example, Mark cribbed his answers from Peter; Mark was cribbing Peter's answers.

I think there's implicitly the idea that Mark is acting without Peter's knowledge/approval.

There is no single word for widespread or organized cheating; if there were, I think it would have appeared in the press by now.

collusion does carry the proper connotation:

secret or illegal cooperation or conspiracy, especially in order to cheat or deceive others; an often secret action taken by two or more parties to achieve an illegal or improper purpose. -AHDEL

Likewise conspiracy (a secret plan by a group to do something unlawful or harmful) can work.

Cheating scandals are not rare enough;

• The 2009 CRCT statistics are overwhelming and allow for no conclusion other than widespread cheating in APS. The BRC expert, Dr. John Fremer, wrote an op-ed article for the AJC in which he said there was widespread, organized cheating in APS. -WSJ
• Governor's Report Details Widespread, Organized Cheating In Atlanta Schools -NPR
• Organized, systematic cheating is the inevitable result of attaching high stakes to standardized tests, and it will continue as long as we're invested in the illusion that the system is working. - Huff Post
• The probe involves about 125 students over cheating on a take-home exam for the course, called Introduction to Congress. Harvard officials called it the biggest such probe in living memory. - Bloomberg.com

If the students are knowingly and deliberately working together, I'd go for "conspiring," especially if there are a lot of them and the cheating is elaborate.

For other cases, you'd probably want a different word such as "copying." I'm afraid it will be difficult to find a single word that covers every situation, other than "cheating" or a synonym.

Cheat and/or copy - perfectly appropriate.

A student cheated during math tests by copying from the student beside him.

For an entire group of students passing answers to one another in an organized effort, I can not think of anything more apt than 'mass-cheating'.

The best thing I can come up with is "To copy something from someone". It is used in the particular way you mentioned as well.

"Mark copied his exam answers from Peter".

"I couldn't be bothered doing my homework, so instead I just copied the correct answers from my mate".

However, this does still convey that what's being done is wrong and essentially cheating although it's less harsh than using the word "cheating".