Since this is a Harry Potter fan club and you want to teach people about rationality, shouldn't you, IDK, tell them about HPMOR or something?
HPMoR page has a link to Spanish translation of the first five chapters... but the link doesn't work. Perhaps google could help?
Then if you are willing to spend some money, you could print a few pages (I guess including Minerva's cat transformation, but not including rape discussion with Draco), bind them together, make a few copies of that, and give it to the fanclub members. It is much easier to read from paper than from the screen. And when they read the start, they will be more likely to read the rest online in English.
Another idea: How about making a "Magic that really works" class about science? Describe magical inventions from stories, and then the corresponding technical things we have today (e.g. Palantír -> television, but better with examples from HP universe). The idea is that we already live in a magical world, we just don't recognize it. And all this magic comes from rational thinking and experiments.
Essentially it is a Dark Arts technique: Use the applause light "magic" and associate it with science and rationality. Describe science as the real magic, and superstition as the false magic. Of course a true magician prefers true magic; the false magic is for ignorant losers.
You didn't tell how old the small kids are. This probably matters. 7 year olds are different from 11 year olds are different from 15 year olds. Whatever you pick as the topic, you should probably come up with a treatment that simpler than what you'd think necessary. And then make it even more simple.
Basic rule of thumb is probably that kids will deal with the concrete a lot better than with abstraction. You might want to start with some regular science popularization about the concrete stuff out there, like the atomic structure of matter, orders of magnitude, stars and planets, animals and evolution. Reading through A Short History of Nearly Everything might give you ideas about this. Maybe proceed to how the scientific method works with hypotheses, experiments and falsification, while trying to keep things very grounded in concrete examples. Also, stuff by Carl Sagan might be good. He had science popularization, and I remember liking his critical thinking book The Demon-Haunted World when I was 15.
I remember taking a course about logic in the context of real-world problems in high school when I was 17, which was the basic Aristotelian binary stuff, and thinking that the stuff seemed ridiculously useless against any sort of real-world problem, both from the obvious problem of mapping simple binary predicates to real-world states of affairs and from the fact that it didn't look much like the way people seemed to be actually reasoning about things. Didn't have any idea about Bayesian reasoning back then. I probably would have been interested in learning about trying to tackle real-world stuff with probabilistic logics at 17, but then again, I also would have thought the Harry Potter books were crap with terrible worldbuilding.
So, basically, good luck, this looks like it might be a lot of work to do well. You're dealing with both the fact that these are kids and that they're not necessarily the sort of people already receptive to this sort of stuff who might end up hanging out at LW.
You didn't tell how old the small kids are. This probably matters. 7 year olds are different from 11 year olds are different from 15 year olds. Whatever you pick as the topic, you should probably come up with a treatment that simpler than what you'd think necessary. And then make it even more simple.
This is something I've struggled with (am still struggling with, really) in my time teaching kids as a volunteer. I already knew the basics of child psychology, remembered more or less what concepts I could expect kids to handle at various stages of development and tried to develop lessons which accounted for their abilities.... but in the beginning, I still way overshot for the younger kids, because I failed to keep in mind that honestly, normal little kids are really dumb. If you treat them like teenagers minus some major reasoning faculties, you're still going to seriously overestimate the caliber of thinking they're likely to be capable of.
My (so far untested, as far as I know) advice is to start off with a talk designed to give people the sense more is possible, i.e. that this stuff is deeply interesting and relevant and worth paying attention to, rather than trying to start teaching them something. Suppose you manage to teach them about a single bias; maybe base rate neglect, or availability bias, or so on. I'm having trouble thinking of a single bias that's exciting enough for people to see benefits from knowing about it, but I know there are several that can be detrimental.
If the audience includes kids, hindsight bias is probably the easiest and most dramatic place to start - you can even do a demonstration with them as the subjects.
Demonstration is good. I'd try to do several.
A favorite of mine is the Forer effect demonstration, where everyone gets a "personalized" horoscope, rates accuracy and then learns they're all identical. Because that is easy and quick, gets a good laugh and directly relates to the Astrology class that is part of the raison d'etre of this course.
You might want to take a look at the techniques/slide decks that people have used when they've attempted similar things in the past. I remember there being at least a few discussion posts on rationality-spreading-tactics.
I think I'm seconding this when I say that one of the most rational of Muggle studies has been magic, in the sense of stage illusionism. There's a long history of stage magicians -- beginning at least with Houdini -- debunking self-declared spiritualists and psychics and so on. James Randi, Penn and Teller, and even Johnny Carson spring to mind.
Update: I was wrong. The first meeting will be this Sunday. I posted these links to the fanclub FB page to get people interested:
https://bookofbadarguments.com/?view=allpages
https://www.smashwords.com/books/view/100799
(note: by far most of the fanclub members are fluent in English)
I think I have come up with a way to make the themes interesting to them. As they already love Harry Potter, they're not afraid to use complicated Latin phrases. So I can say something like, "The key to casting a successful Modus Ponens spell is to first summon the Antecedens and then proceed to the Consequens. Never summon Consequens first, as it will cause the spell to blow up in your face." Then we can study some defensive techniques against the Ad Hominem curse.
I'm not sure Muggle Studies is going to be the name to best win people over to rationality and critical thinking, even in the context of a Harry Potter fanclub.
There could be an interesting angle there for making people look at the mundane detail of real-world stuff they don't usually pay attention to by framing the discussion into the viewpoint of befuddled wizards who have manged to figure the thing out but can't use the "of course we all already know what this is" cultural familiarity.
Like, how would a clever wizard stuck with a basically medieval technology level (correctly) explain how electricity and electrical appliances work to another wizard. Or indoor plumbing, or why doctors should disinfect their hands.
The phrase "X Studies" refers to lessons about X, not lessons for X. For example, in Harry Potter (or at least in HPMoR; I'm not so familiar with the original), "Muggle Studies" refers to classes that wizards take to learn about Muggles.
So you're either misusing this phrase, or using "Muggle" to refer to LWers instead of non-LWers.
That's precisely the point---to look at those strange creatures, the Muggles, see how they eradicated smallpox and put men on the Moon, and ask: how do they do such amazing things using only their brains?
It seems I misunderstood. It didn't occur to me that you might have meant "Muggles" literally (i.e. exactly as used in Harry Potter). My apologies.
Some months ago, when I was preparing the first drafts of this course, I compiled a "recommended reading" list. What do you think?
http://estudiosmugglespluma.blogspot.com/p/lecturas-recomendadas.html
What do you think?
The nonfiction list looks nice, but it's probably looking quite formidable as it is for someone with no idea what the books are about. And the selection in general looks like something you'd want to give to a university student or an above average high-schooler, who of course needs to read English fluently. If you're going to give this to people who aren't expected to know the books already, you probably want to have a bit of text for each book telling what it's about and why it's on the list.
And for random people, the best case scenario is probably that they will get one of the books and read some of it, so you might want to split off a shorter list of five or so books you recommend people will read first, so that they won't have quite as hard a time figuring out where to start.
Random additional fiction suggestions: Greg Egan's Permutation City (theory of identity, computation) and Distress (philosophy of science, epistemology). Stanislaw Lem's Cyberiad (robot fables), His Master's Voice (the process of science and mathematics) and Solaris (the limits of science when you run into aliens who won't play along). Ted Chiang's Stories of Your Life and Others (short stories, the nature of reality, messing with human cognition). Peter Watts' Blindsight (humans are mostly crazy robots made of meat; delicious, delicious meat). Walter Jon Williams' Aristoi (cybernetic mental upgrades beat medieval mooks). Karl Schroeder's Ventus (magic is runaway nanotech the medieval mooks are confused about, then things get weird, could be a jumping point from Harry Potter). Neal Stephenson's Cryptonomicon (you can do cool shit with math). Vernor Vinge's Rainbows End (VR internet 20 minutes into the future has simulated Harry Potter magic interfaces, popular culture magic as a thing that ends up shaping actual tech).
At my local Harry Potter fanclub (Bogotá, Colombia) some members teach "classes" on subjects they're passionate about. We've had informal courses on history, creative writing, English, etc. But recently some other classes have appeared that have made me worry seriously: astrology, divination, ancient runes, and all other sorts of nonsense. They're not taught as folklorical pieces of the past, but as serious practices that are supposed to actually work. I think this is particularly dangerous for the small kids that comprise the majority of the fanclub and still need help learning that magic doesn't exist.
So I proposed the fanclub chief that I could teach a Muggle Studies class: logic, critical thinking, philosophy of science, etc. In two weeks we'll have our first class, and I intend to begin talking about the most common biases. I already downloaded this website's PDF guide to holding a Less Wrong meeting. Aside from that, what can you suggest for a successful Muggles Studies course?