Some secret codes
Problem
Here is the alphabet:
a b c d e f g h i j k l m n o p q r s t u v w x y z
I have made a code that means we move $3$ places to the left to discover what the code stands for. But what will happen to
a b c ?
They pick up the letters left over at the end of the alphabet so that they become
x y z
sdw - d - fdnh,
wkh - zhvw - zlqg - eorzv,
brx - duh - zrunlqj - kdug
Can you invent some messages of your own?
Can you create some different ways of coding?
Getting Started
You could try writing the letters round in a circle so that it is easier to count forwards and backwards. Use the wheel we have created to help you.
Student Solutions
Alex from Mortimer St. Mary's School in England sent in a challenge for us at Nrich which turned out to be the word, antidisestablishmentarianism, once thought to be the longest English word. Can you see what the code was for this very long word?
The solutions of "pat a cake, the west wind blows, you are working hard" were sent in by many of you. Here are the ones that we received; Martin and Jonah from Goodleigh School; Christy, Charlie and Callum from St. Cecilia's Wandsworth; SJF Y6 Maths from G&T School; Zetta from Thomas's Battersea; Dan from Whitby Community School; Tallulah, Anna and Aishwarya from Salcombe Prep School; Kavi from St. James the Great; Kavya from Hymers College; Suchita from Elsley School; Tom and Henry from Redgate School and Toony $5/4S$ Toongabbie Public School Australia.
Sana and Freya from The British Manila in the Philippines wrote the following:
sdw - d - fdnh = pat a cake
wkh - zhvw - zlqg - eorzv = the west wind blows
brx - duh - zrunlqj - kdug = you are working hard
nrich is awesome = qulfk - lv - dzhvrph
world peace = zruog - shdfh
math is fun = pdwk - lv - ixq
Think of a word in the dictionary then take the one before it and spell
that word backwards e.g.
a = starter word
zoom-lens = word before a in dictionary
a = snel-mooz
(for word before starter word spelt backwards).
Year 5 from St. John's wrote:
1.PAT-A-CAKE
2.THE-WEST-WIND-BLOWS
3.YOU-ARE-WORKING-HARD
WE FOUND OUT NRICH'S QUESTIONS BY PRINTING THE CODE WHEEL OUT. WE USED IT TO FIGURE OUT THE ANSWERS. WE FOUND OUT ABOUT MORSE CODE AND MADE OUR OWN CODE.
.-- . .- .-. . ..- ... .. -. --. -- --- .-. ... . -.-. --- -.. . ---
-.
-. .-. .. -.-. ....
THAT EQUALS:
WE ARE USING MORSE CODE ON NRICH
Thank you for all of these. It shows you really worked hard but enjoyed it along the way. How about sending in to next month's challenges?
Teachers' Resources
Some Secret Codes
Here is the alphabet:
a b c d e f g h i j k l m n o p q r s t u v w x y z
I have made a code that means we move $3$ places to the left to discover what the code stands for. But what will happen to
a b c ?
They pick up the letters left over at the end of the alphabet so that they become
x y z
sdw - d - fdnh,
wkh - zhvw - zlqg - eorzv,
brx - duh - zrunlqj - kdug
Can you invent some messages of your own?
Can you create some different ways of coding?
Why do this problem?
Possible approach
Key questions
Possible extension
Possible support