Codes and Codebreaking

What Was in the Box?

Age 5 to 7
Challenge Level

This big box adds something to any number that goes into it. If you know the numbers that come out, what addition might be going on in the box?

What's in a Name?

Age 5 to 7
Challenge Level

Here's a very elementary code that requires young children to read a table, and look for similarities and differences.

What's Happening?

Age 5 to 7
Challenge Level

Shapes are added to other shapes. Can you see what is happening? What is the rule?

Cracking Codes

Age 5 to 11

Jenny Murray describes how she developed her interest in making and breaking codes.

Some Secret Codes

Age 7 to 11
Challenge Level

Can you follow the rule to decode the messages?

Unlocking the Case

Age 7 to 11
Challenge Level

A case is found with a combination lock. There is one clue about the number needed to open the case. Can you find the number and open the case?

It's a Scrabble

Age 7 to 11
Challenge Level

Letters have different values in Scrabble - how are they decided upon? And would the values be the same for other languages?

Make 24

Age 7 to 14
Challenge Level

A card game for 2 or 4 players that will test your speedy arithmetic skills!

Substitution Cipher

Age 11 to 14
Challenge Level

Find the frequency distribution for ordinary English, and use it to help you crack the code.

The Best Card Trick?

Age 11 to 16
Challenge Level

Time for a little mathemagic! Choose any five cards from a pack and show four of them to your partner. How can they work out the fifth?

Substitution Transposed

Age 11 to 16
Challenge Level

Substitution and Transposition all in one! How fiendish can these codes get?

Transposition Cipher

Age 11 to 16
Challenge Level

Can you work out what size grid you need to read our secret message?

Secondary Cipher Challenge Part 1

Age 11 to 16
Challenge Level

Here is the start of a six-part challenge. Can you get to the end and crack the final message?

Secret Transmissions

Age 14 to 16
Challenge Level

How can Agent X transmit data on a faulty line and be sure that her message will get through?

Keeping it Safe and Quiet

Age 14 to 18

Simon Singh describes PKC, its origins, and why the science of code making and breaking is such a secret occupation.

Probably a Code?

Age 16 to 18
Challenge Level

Is the regularity shown in this encoded message noise or structure?

Stage 5 Cipher Challenge

Age 16 to 18
Challenge Level

Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?

More Secret Transmissions

Age 16 to 18
Challenge Level

In 'Secret Transmissions', Agent X could send four-digit codes error free. Can you devise an error-correcting system for codes with more than four digits?