# The x4 Principles of Coding

## Let’s begin: Back to first principles

The x4 Principles of Coding are the basic skills needed to begin to code.  I give my students basic tasks that use these principles, firstly using Scratch.  At about year 9 I move my students onto new languages such as Sniff, Arduino (C++) and Python, but again I start by teaching these x4 principles:

• Variables
• Input/Output
• Loops
• Decisions

### Explanation

• Variables
• “Enables a computer to remember things”
• Variables are place-holders that can store a value that can be changed
• eg. Used in maths: if x = 3 and y = x+2 what is the value of y? etc.
• Input/Output
• Telling a computer something
• Enabling a computer to tell you something
• Loops
• Repeating instructions
• There are two ways to repeat instructions:
• WHILE loop
• loop while a condition is true
• eg. WHILE iAmHungry()=True LOOP eatPasta() END
• FOR loop
• loop a specified number of times
• eg. FOR x = 1 to 5 LOOP
• Decisions
• IF <something is true> THEN <do action 1> ELSE <do action 2> END
• eg. IF isIsRaining() THEN wearAHat() END IF

### More examples can be found in Resources  