The title sounds like an unpleasant experience at Hogwarts but is in fact something I'm noticing in my own writing as I edit.
My blog posts have reduced in frequency because I've been deep in edits for Book 2, working title The Magnesia Sanction. (The title will change before it sees production). I'm at major revision #8, and I think This Is It, The Final Version. Of course I thought the same for revisions 2 through 7, so what would I know, but in any case I've printed the entire ms and am pacing back and forth in my office, reading the whole book aloud. I find reading aloud essential to
a) get the flow and rhythm right; and
b) find redundant words which I don't need.
BJ Muntain warned me to drink enough so my voice doesn't go hoarse while reading 305 pages. Never fear, each lap takes me past the beer fridge.
What I'm noticing as I read is all my expository lumps are preceded by a Dorothy Dixer.
Wikipedia, which as we all know is never wrong, tells me Dorothy Dix was an early agony columnist in the US. How her name came to be associated with faux questions in the Australian parliament I don't know, but it is nevertheless the case that when an Australian Government minister wants to make a set-piece speech during question time, he arranges for a colleague to ask a totally fake question which allows the minister to produce his prepared speech. This is a cheat, but they do it all the time, and such a fake question is called a Dorothy Dixer.
Expository Lumps are a (relatively) benign cancer which must be excised for the good of the book. One character goes on and on telling another character something they probably should already know. The real target is the reader, who certainly doesn't know whatever is being explained. This is the author's dodgy way of delivering information direct into the reader's brain.
Expository Lump is a particular disease in science fiction. As you know, Captain, the hyperdrive works by folding space into tiny packets of... followed by two pages of exposition. Expository Lump is also a threat in historical writing. As you know, Pericles, the Athenians hold their meetings at the Pnyx, where the people vote...
As you know is the time-honoured method for introducing an expository lump. (If you're a writer, this would be a good moment to do a quick global search on your own ms.) I don't write as you know. Instead, one of my characters asks a really dumb question, purely so another character can tell the reader something.
Yep, that's a Dorothy Dixer.
Incredibly, I don't notice when I write these things in the first draft, but when I read aloud they stand out like a sore thumb. The good news is, the ensuing expository lump is almost never required. My readers, who are much smarter than me, can work out an amazing amount purely from context. When I find an expository lump I remove the lot, then stand back to see if the text still makes sense. Usually it does. At worst, it might need a sentence or two. The other trick which works is to change the scene setting or some other passive element of the story to deliver information by implication.