Shapes are added to other shapes. Can you see what is happening? What is the rule?
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?
Can you follow the rule to decode the messages?
Here's a very elementary code that requires young children to read a table, and look for similarities and differences.
Jenny Murray describes how she developed her interest in making and breaking codes.
I was looking at the number plate of a car parked outside. Using my special code S208VBJ adds to 65. Can you crack my code and use it to find out what both of these number plates add up to?
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?
The Enigma Project's James Grime has created a video code challenge. Watch it here!
This article describes the underlying mathematical ideas and skills involved in the important mathematical application of coding.