My daughter’s elementary school offers a project week close to the end of the school year on alternate years. Each teacher and the parents of each class work out a particular idea, and the kids choose which project to be a part of.
So much for the history. The wicked cool idea that the parents of our class are working on (judging from the fact that the group size spilled over to fill up three large groups instead of the one small one we thought we were offering!) is Detective School. Other mothers are working on preparing crafts like making periscopes and dusting for fingerprints and taking casts of footprints, and my contribution is to work out codes and invisible inks so the kids can send secret messages to one another.
So far, I’ve been researching invisible inks such as milk, lemon juice, and vinegar, which become visible when heated over a light bulb, and come up with a few ideas for secret codes: putting together an alphabet wheel to create an unbreakable code (which has the advantage of keeping little hands busy for a while), using a ruler and writing your message out by putting one letter over each half-centimeter mark, and then filling in random letters in between (decode with your own ruler), and using backwards writing meant to be viewed in a mirror.
I’ve also put together a few ideas for sly presentations: using the invisible ink in between the lines of an innocent note, or on the envelope rather than on the letter itself.
Any other ideas for 8-year-old spies and gumshoes?
And do I need to mention how much fun all of this is?
There is a special chemical based on the Phenolphtalein(which you can make yourself from red cabbage and other plants, or buy in the chemical supply store). You write on a paper in one shade (pink I think) and if you want to read it, breathe on it - the acid in your breath will make it change colour. I never tried this, but it was in a book on how to make cheat sheets for school.
There are also some books (which titles I have forgotten now, of course) in the local library section which give the history of codes as well as examples.
The Jule Vernes revenge novel/ Count Christo knockoff Matthias Sandorf describes in detail an “unbreakable” code (the bad guys break in to get the key).
Another method was the code stick: a stripe of pergament/papyrus was rolled around a stick of certain thickness and then the message written on it. Once unrolled, you couldn’t read the message, you needed a stick of the right diameter to coil it again.
The drastic method (which you might tell, but probably don’t want to use) was to shave somebody’s head, tatoo the message onto it, and wait till the hair had grown back again.
If you are talking about the envelopes, the placement of stamps has often been used as cipher. There are some stories where one stamp lying on its side, the next stamp on its head, and the combination of a green, brown and blue stamp meant a certain message.
This is already related to a mentalist trick of mind-reading: certain codephrases he uses with his assistant. In a Tom Brown (?) novel, the smart hero of the novel explained to his school mates how a mind-reading sorcerer had done that, and even demonstrated it by making up his own code phrases (about 20) with his assistant and correctly reading the things the assistant was holding up while blindfolded.
Sherlock Holmes had a story (don’t remember the title) where the book code was used (one of the few really unbreakable ones), and of course was able to deduce which book was meant.
You take a book where both sender and receiver have the same edition and then write down page number, line number, number of word to compose your message. You can then disguise the message as simple addition like a grocery list or telephone numbers to add another layer.
Will you tell them about the Navajo code talkers, or is the background too gruseome for 8 year olds?
Use all the code systems you created, and add a code at the beggining of the message to indicate to the reader which method was used. So if the first two letters are AA the reader knows to grab his ruler, but if the first two are QR then they get out the alphabet wheel.
You could do the same thing for the invisable ink. Have them always write the plain text message double spaced. Then depending on how the plain text letter starts it tells the reader where to look for the invisable ink. So if the message starts “Dear Reader,” They know to heat the letter and find the hidden ink between the lines on the page. If the letter starts with “Hello Reader” They know to heat the envolope to find the message.
This may seem off topic, but it might be fun for 8 year olds.
My latest knitting project is illusion knitting (also called shadow knitting) The idea is that you use two colors of yarn and a pattern of knits and purls to create a message–usually an image–only visible at an angle. When viewed straight on, it’s a simple stripe, but at an angle, you can see kitty cats and witches hats, and all kinds of stuff.
And if it’s ZB, they’d better know where that night’s one-time pad is, and if it’s OŠ, they’d better have brushed up on their Czech.
And you could take infrared pictures or shine ultraviolet light on the message to see whether the ‘invisible’ ink shows up under different lighting. You can get UV flashlights at electronics stores (apparently cat pee fluoresces under UV; does human pee?); and many digital cameras are sensitive to UV.
Then do the same with a banknote.
This would be a good introduction to the technological arms race between hiders and exposers.
Heh–yesterday I did an impromptu lesson in secret codes for my 8-year-olds, too. It was nowhere near as cool as your much more planned lesson, and next year I’m totally stealing your idea.
That said, I’d recommend keeping it simple: second-graders have a wide range of cognitive abilities, and while some of them quickly ran with my most advanced substitution code idea (substituting each letter with a symbol), others took nearly an hour just to create the most basic code (write each letter in order, put an = by each, then write the alphabet again starting at a different letter, so that, e.g., A=E, B=F, C=G, etc.). Even though I specifically told them, “Don’t write A=A,” I seriously had one kid who did that.
They also really enjoyed the wrap-a-strip-of-paper-around-a-marker code.
If you can have layered instruction, that’d be best. That is, have very simple codes that kids do first, and when the smarties finish those, have permutations they can explore.
Great ideas, everyone, thanks so much! Between this and the research I’ve been doing, I’ve got 10 different codes to try out and two different invisible ink categories, plus sneaky tricks for how to hide where the message is hidden. I need to plan four different projects for the four full days of the week, and I’m thinking to start simply and work up in complexity. We could have a simple lemon juice code on the first day as well as a code in which the vowels of the message are dropped and then the message is written backwards, for example, and then add on twists as the week goes on.
Did you know that the NSA has a kids’ page with codes and ciphers? What on earth did we ever do for research before the internet?
Heh. I’m not worried so much about the parents being squeamish as the parents knowing where I live and tracking me down to do me harm after their kids write all over the house with their own urine. I read about other bodily fluids being used as invisible inks, too, and I’m REALLY not going there, for my own sake!
And as much as I love the idea of talking about different codes used over the ages, I’m leary of an American mother talking to German kids about a method used by Americans in World War II, albeit not against Germans (to my knowledge). I’m thinking it’s probably best to stick with the methods and let them learn the history when they’re older.
I’ve always liked “one-time-pad” codes. Take a book, and then cut out openings in a sheet of paper over the letters that make up your message. The message can only be decoded by knowing which book and which page is the key.
Technically a “one-time pad” refers to a substitution cipher where there is a non-repeating pattern of substitutions–the pattern is randomly generated, pre-shared, and only used once.
I can’t remember the term for what you’re describing. I had thought it was “platen cipher” but Google refuses to validate me with a cite.
The other way to do what you’re describing is have a sheet with pre-cut holes in it, write the message on an sheet of paper under the code sheet (only in the cut-out holes), then figure out a way to compose a letter around the hidden message that sounds plausible. Decode by placing a copy of the sheet with cutouts over the normal-looking letter.
This is the method used in the Mathias Sandorf novel I linked above: a piece of cardboard with holes is placed over the text to be coded, the letters visible in the holes are written down, the square is turned 90% to the right, so that new letters are visible, write down, turn, repeat. At the end, if your holes are placed correctly (which you let the smart kids figure out themselves so that the holes don’t overlap when you turn it three times) all letters will have been written down.
Supposedly, you need to have the square at hand to decode, though I once tried and if you know that this method was used and the text itself is clear, you can try and work out the order.
Of course, that’s an additional layer: first code the message by putting it into another language or similar, then cipher the text using the alphabet wheel or the book method, then write that with invisible ink onto the envelope…
Are you going to tell them also about steganography - hiding information in a picture by changing the hues? I don’t know if it can be done without a computer program, though placement of stamps on an envelope is a similar low-tech idea of hiding information in a place where nobody would normally look.
I would also borrow a dozen or so ??? novels and Sherlock Holmes books from the library as general gumshoe reading. (I could recommend you some good children’s detective stories from german authors, but I doubt they have been translated - most translation seems to go the other way). The ??? also have an detecting handbook (in several editions) where they teach the basics of the craft.
If the kids have access to the internet, you could show them wheresgeorge, where you can track dollar bills - not code, but practical sleuthing that they can continue after the project is over.
Oh, I see now you are in Darmstadt! Doh. I thought all the time you were American. In that case, I recommend the following detective novels:
Wolfgang Ecke has lots of humourus ones. One series is about a detective called Perry Clifton in London, with a young boy as sidekick. Nicely done. And several books called Ratekrimis, to guess along.
Jo Pestum has the Kater series (male cat) about a detective Katzbach who is nicknamed Kater. These are darker and realistic about how crime looks like in the real world, causes and effects.
And Christine Nöstlingers Der Denker greift ein - in an elementary school in Vienna, things are stolen in class, and (naturally, sadly) suspicion falls on the “Sir”, the mixed half-black kid. The thinker (Denker), a friend of the Sir, sets about to clear the case to help his friend (he wasn’t interested in petty crime before), and finds out that one lonely boy, trying to befriend an older boy, has stolen for recognition. At the end, the thinker ponders that some people are very hard to like, but need to be liked, and there should be a way to like them although it’s difficult, so they aren’t cut off from society.
Have you talked with the teachers about how much codes, esp. things like invisible ink, are going to overlap with the methods used to create cheat sheets (Spickzettel)? Things have moved far beyond what we did. Today, you print your cheat sheet from the computer and paste it onto your mineral water bottle, looking like the official label. Or you buy transfer paper and put the cheat sheet onto … practically every surface. Okay, the heat-sensitive inks probably won’t be used during tests … but the different codes can also be used in class to talk to each other.
Are you going to show them any hand signs - not the old-fashioned double-hand alphabet, but officially DGS or the inter-tribal hand language of the Prarie Indians (though that was the opposite of a cipher, to be exact). Baseball managers signaling to the players would be an example - and there was a scandal some time ago when an American football team taped the opposite team’s coach to break the code - but that’s difficult to transplant.
Since ciphers are related to Math, I wonder if the Math Experiment section of that new Science Museum in Bremen has a section to try? Even if you can’t visit directly, they might have stuff on their website to download, or send paper things if you ask.
The Munich Technical University, together with the Deutsche Museum, does special summer holiday activites with Math/ code, but off-hand I don’t know who to contact for that.
Reminds me both of semaphore - the flag language used by the navy before - and the Sherlock Holmes story “The Dancing Men”, where stick-figures of little men are used for substitution.
The European site to track banknotes (inspired by wheresgeorge) is eurobilltracker. Though you have to enter a lot of bills before you get a hit (not many people know about it yet, and it’s not a good idea to write the web adress on the bills, because banks often pull bills with writing on them and destroy them), it’s still interesting to learn what the production code on the front and the serial number on the back codes as to country of origin and printing company. They will learn something about money that very, very few adults usually know, giving them an opportunity to be smart-asses.
The competing site of eurobilltrackinghas a lot of statistics and information about the bills.
Great heavens, that’s an oddity! I’m not in Darmstadt any longer; I just updated my location to Bad Homburg. I didn’t even realize my location was in my profile. Actually, I didn’t realize I had a profile. Kids today and their new-fangled profile fields!
The second part is true, though; I’m American. My daughter’s school is a normal German Grundschule. Do you think I can convince them that English is a secret code and hold my sections in my better language?
To be accurate, the project is “Die Drei Fragezeichen” (or better, “Die Drei ???”), but I thought Detective School would convey the right information without getting needlessly confusing.
Interesting what you say about cheat sheets – it’s probably better if I don’t mention that to the kids!
But historically and technically, a one-time pad was a different track in the spy game, used extensivly in WWII by the Allies (I think without looking up details). Before, the research focused on making the codes harder and harder to break (and taking longer and longer) - resulting in things like Enigma.
The one-time pad is the directly opposite approach: you mass-produce a pad with lots of rather simple codes - substitution - but after each message, you rip of and destroy the top paper and use the next one. It doesn’t matter that each code is easy to break, because if the enemy manages to decode one message, he still doesn’t know how the next message will be encoded, and there’s no chance of slipping a false message in once the enemy has broken the code. Only the people who have that specific pad can decode the message correctly.
And surely you didn’t mean to suggest cutting holes in the book?
