Firstly, because it’s easier to remember half-a-dozen powerful ideas (culture, socialisation, roles, values, norms, social control…) than the page of text in which they’re embedded.
Secondly, if you choose powerful Key Words, by bringing them to mind you can use them to unlock a massive amount of associated stored information. A simple way to demonstrate this is to write the Key Word “Family” (or “Education”, “Deviance” or whatever) in the centre of a whiteboard and ask your students to add further connected key ideas – you’ll quickly build-up a hugely-impressive Key Word Map of whatever topic they’re familiar with.
In “The Good Old Days” (some indeterminate point in the past that I fondly like to think was “Better Than Now” (but actually wasn’t) the process of creating Key Word lists was time-consuming and dull. Basically, it involved laboriously writing (or typing if you were posh) lists of words onto index cards that you could then carry around and whip-out at inappropriate moments to Read’n’Remember (or ruin by accidentally dropping them into your tea. One of the two).
In the Age of The Internet, however, it’s possible to create highly-visual Word Clouds (similar to the Tags Cloud at the bottom right of this page) based on significant Key Words with a few simple keystrokes. Using a site like Wordclouds, for example, you just type the words you want to Cloud and save the resulting Word Cloud in a wide range of formats (as .jpgs, for example, or as .pdf documents). If you want to do something a bit more sophisticated there are a wide range of formatting options to play around with, plus the facility to cut-and-paste a text file into the creator, which will save you even more time – although depending on the file content you may have to the resulting Cloud to get something useful.
If you save your Word Clouds as pictures (e.g. as .jpgs or.png files) you can store on your ‘phone or tablet if you plan to use them as “revision cards”.
Alternatively, if you’re a teacher looking to brighten-up their classroom you can create Word Clouds to use as wall posters.