There is lots of advice around about how to make your text readable. For example, don’t have long sentences, use simple words, and numerous other injunctions. However, I really think that one-size-fits-all advice is inappropriate, because it depends on who your audience is, and what you’re hoping to achieve.
For example, on a writing course I once rendered a near-incomprehensible press release into a one that, according to the built-in readability tools in Word, could be understood by an 11 year-old. That was a good thing, from the point of view that in order to read a British broadsheet paper these days you need a reading age of 11, according to The Readable Blog.
However, according to the same article,
In other words, what is readable by a particular age group today may not be readable by that same age group tomorrow. Therefore, if you are aiming for a general (newspaper) audience, the goalpost will keep changing.
I write for a specialist rather than a general audience. On this writing website I assume that the average reader is fairly literate and articulate. For my education blog, I also make the assumption that the average reader will be well-educated, by which I mean either qualified as a teacher or at least able to discuss educational issues sensibly.
I know that these assumptions exclude some people, but if you think about it, why would I wish to write articles about writing for people who can’t read very well? Why would I want to write articles about education for people who don’t “get” education?
Thus “readability” depends on your audience. For example, my article about how to convert an offline course to an online one has quite a higher-than-average reading age according to most measures. Mind you, the results differ according to which tool you use, from a reading age of around 11 to one of around 17. The average, as in most common, appears to be in the range of grades 9 to 10, or roughly 14 to 15 year olds.
As for using simple words, I don’t believe in making text unduly complicated for the sake of it, but the better advice would be to use the words that are the most appropriate, and if that includes words that have a particular meaning in that context then so be it. (For example, the word “exclusion” has a different meaning in the worlds of education, social services, and everyday life.)
Having said all that, it’s by no means a bad idea to use tools to check the readability of your text. If you use Word, you’ll find the readability tool hidden in the Options section of the Spelling and Grammar checker for some reason. Once you’ve checked the document you will see a result like this:
Unfortunately, you’ll then have to look up what the Flesch scores mean. A good starting point is the Readability website, which also has a useful selection of other tools, such as the readability graph above.