Computer Science

Subject: Python Turtle Graphics

Skills

Students are able to create simple computer programs using the Python Turtle Graphics (PTG) module, which extends on existing Python skills to reinforce:

• Sequence - input and output and basic image generation
• Selection – modification of behaviour within the code for selective execution of code paths
• Iteration – the use of looping constructs to create dynamic images.
• Computational mathematical operations to manipulate screen coordinates

To be able to implement sub-routines in program code

To be able to develop programs for image generation

To be able to debug and correct problems in their code

To be able to annotate code using appropriate terminology and technical language

Knowledge

Know how to implement Python Turtle Graphic module code by importing the PTG module and referencing its library of functions

Know how to utilise the PTG syntax to create images and draw custom shapes:

• Movement commands: left, right, forward
• Pen commands: pen-up, pen-down, colour, size
• Shape Commands: circle, square, fill and end fill

Understand how to nest loops within loops for kaleidoscopic image creation

Know how to implement mathematical operations as part of plotting images on the screen

Know how produce algorithmic solutions for specific problems based on requirement statements

Know the purpose of subroutines in a program, and understand how to implement sub-routines

Understand the importance of ‘commenting’ code and documentation

Rationale

This unit extends and reinforces the students’ programming skills using the Python PTG extension.   It applies their learning of Python and computational thinking to some motivating tasks where they create ever more creative and colourful shapes using the Turtle module.

By the end of the unit, students will be able to design their own images using short snippets of code, as well as debug, annotate and document their code.  They are also encouraged to explain their designs, so as to become conscious of the algorithms they are creating.  

We believe that creating patterns and shapes in Python is an excellent pathway to learning the programming techniques used in the higher year groups, because the students often become so determined to make better and better shapes, they start using more complex techniques.  For example, it is not uncommon in this unit to see students coding in nested loops and making use of subroutines in their code – if they master these techniques, they will thrive at GCSE.

Subject: Python programming with PRIMM (units 8-13)

Skills

Being able to apply some pre-intermediate programming techniques to write simple computer programs which solve real world problems.

Being able to investigate, modify and write programs which:

• Branch according to input
• Loop according to counters
• Perform logical evaluations in programs

Being able to predict the output of an unseen program containing elementary programming techniques such as branching and count-controlled iteration.

Knowledge

Understand the use of one basic programming construct used to control the flow of a program: selection

Understand the use of another basic programming construct used to control the flow of a program: iteration (count-controlled loops)

Understand how the common arithmetic and Boolean operators are applied in selection statements

Rationale

Learning Computing has, at its heart, learning how to program computers to perform tasks for us.  This goes beyond writing instructions that the computer can reliably execute, and addresses how to write programs that branch in various directions depending on the data the user inputs, as well as programs that perform tasks again and again, as many times as we wish.

In Year 8, this means spending considerable time writing programs which branch and iterate.  Concepts such as these take a long time to master, and a resilient approach is required as the branches and loops that you code fail before your eyes.  This unit features three lessons working through tasks that develop understanding of branching, and applies this techniques to a series of more challenging tasks.  It then does the same for count-controlled iteration, also applying this technique to a series of increasingly complex tasks.

By engaging with these lessons, a student should be able to write useful programs which are versatile enough to perform different tasks depending on the user input, and which perform tasks again and again until the programmer says they are done.  After all, the processor can handle over 3 billion instructions per second, and will not complain no matter how many times it is asked to do something.