Here is a problem:

“Calculate the perimeter

Design and implement a program that allows the user to enter 2 numbers representing the width and length of a rectangle. The program calculates and displays the perimeter of the rectangle.”

Where do you start? Asking these x3 questions:

- What inputs is the system expecting?
- What is the system expected to output?
- How will the inputs be processed to make the output?

##### I use this framework on the whiteboard and encourage my students to do the same every problem they encounter.

###### Input

- Width of rectangle
- Height of rectangle

###### Processing

- Perimeter of rectangle = (width x 2) + (height x 2)

###### Output

- Perimeter of rectangle

Further details about this approach along with a range of assessed challenge sheets and a student Python crib sheet can be found in my book “Teaching to code: Newbie to GCSE”