Jen Alexander
Secret Codes
I can help with the secret code (mathematically known as cryptography)
part. You could use some of the "codes" I describe as easy
"Oh-you're-bored-here-try-this" games, or gathering games...
Spiral Codes:
One of the easiest codes to do involves a two brooms with the exact same
handle size (or other long and thin cylindrical objects), and a long
strip of paper. The girls wrap the paper around the broom handle, and
in a spiral shaped fashion so that the part of the handle is completed
wrapped in paper. The girls can write their message, and remove the
paper... and suddenly, the long strip of paper has transformed into a
jumble of letters or your ... secret code. The tape can be passed to
the other group (with matching broom handle size) who can wrap their
broomstick with the paper, and the message will appear. :-) You could
use items of varying diameters to show how it won't work unless the
handles are the same size.
Invisible Ink:
I think you can mix lemon juice and water, write on white paper with a
toothpick, let the message dry, and "see" your secret message as you
hold it up to the light...
Caesar Cipher:
Caesar was said to have used this code himself... This is just a
"mapping" of letters, and most kids are familiar with it. In Caesar's
case, A=C, B=D, C=E, D=F, etc. So the word BAD = DCF. You could have
the girls team up, and have each team pick a letter to "map" to... A=J,
A=Q, etc. and have them "encrypt" an short message. They could then
give their encrypted message to another team to "decrypt" (encrypt and
decrypt are the words used in the industry). The girls probably
wouldn't pick A=C (if that is your example), (and definitely not A=A),
so that leaves 24 letters left to try. Four girls could try six codes
pretty easily... if the first word doesn't make sense, then they stop.
You could turn it into a contest... Use parts of your promise and law
for the messages, or work clues into the messages if you want to do them
yourself. (Note: This is a very easy code to break. You might want to
explain to the girls that very few people could read in Caesar's era,
and so this code worked quite well...)
Permutation Cipher:
This is a more advanced version of the Caesar Cipher. Instead of
picking A=C, B=D, you can map to random letters ... A=C and B=F and
C=Z... Here is something you could give the girls...
---
We will use math and statistics to help us. Count how many times each
letter of the alphabet appears in your message.
E is the most used letter in the English languge. Which letter is used
most often in your code? Write an E underneath that letter every time
it appears in your message.
The second most common letter is probably 'T'. Write an T underneath
that letter every time it appears in your message.
A very common word in English is 'THE'. If this word appears several
times in the message you should be able to guess what letter represents
'H'.
A strong clue in breaking a code is some knowledge of certain words that
are likely to appear in it. For instance, this message mentions our
camp. If you can find where the word 'GUIDE' appears, you will know
what several more letters represent. You may also wish to look for the
word 'CAMP'.
The most frequent letters used in the English language are: E, T, A, O,
and N. See if you can use this information to find out which letters
stand for O and N.
Solving the remaining letters is now up to you. What does the message
say?
---
Technically, you don't even need to use letters in your code.. You could
use little pictures or stickmen in various forms (Did anyone else read
that Trixie Beldon mystery when they were little?) ... anything which
can be recognzined and counted. :-)
The girls should be able to break your codes here... Make sure that
these instructions will "work" on your message, though! :-)