Back somewhere around the Middle Ages when I was in school cheating generally meant copying off another person's test or homework. Occasionally someone had a cheat sheet. As time went on cheat sheets back smaller and more innovative. Girls wrote them on their legs so they could just flip their skirt up a bit. People put them in their shoes but I don't see how they could see them. Guys put them in watch faces and on the underside of their ties.
Plagiarizing an essay generally meant copying from the encyclopedia, Cliff's Notes or another person. Sometimes people copies a textbook.
People whispered answers or coughed them to each other, haaaackk a or kkkkkkkks b. They still do that.
But today's technology has given students more innovative means of cheating. I have never been what I consider a gold medalist at catching cheating but I have caught all of the above at some point or another.
As of late, I caught people using their cell phones to text each other answers or to copy the test by taking photographs of it. In the Middle Ages, people announced there weren't enough tests in the row and asked for another which they took out of the room, which is why I handed each person his or her test personally. In the past people wrote outlines on their desks (more on that later in Aristotle in the classroom), another reason I handed each person his or her test personally. Cheat sheets became even smaller because of the availability of small fonts on the computer and one person could now generate multiple versions of the same cheat sheet. Therefore, you don't even have to make your own anymore.
People look for more obscure essays to copy from the Internet and they send them to each other and change the font size and the opening sentence. People also do things like put a title page on an essay and then copy over something like Sports Illustrated hoping the teacher only checked for length.
Information can also be hidden in calculators, so they can't be on the desk except in math classes. IPods have some of the same capabilities as well.
As technology grows so do the methods of cheating.