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1CP2-CT-6.2 Planning composing and debugging Turtle programs

Part 2 of 2 · 1CP2-CT-6 · Turtle problem solving

The planning and debugging worksheet for the Turtle topic, preparing students for the practical checkpoint that follows it.

Students will:

  • control outline, fill and circle drawing
  • compose a scene in layers, in a deliberate drawing order
  • use parameters to build related objects from one subprogram
  • debug from the visible symptom back to the cause
  • plan a drawing before constructing it

The checkpoint itself stays in the Workspace, where a teacher can inspect both the program and the picture it made.

Inside: 7 explanation cells, 3 multiple-choice questions, 1 fill-in-the-blanks cell and 6 written answers. 20 marks, about 45 minutes.

Series: 1CP2-CT-6 · Turtle problem solving, part 2 of 2.

Shared by Coding PathwayVerified teacher

  • 17 cells
  • About 45 minutes
  • CC BY-SA 4.0
  • Shared 17 Aug 2026

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The whole resource, exactly as a class sees it. Answers and marking are held back.

Planning, composing and debugging Turtle programs

This worksheet prepares you for the practical Turtle checkpoint. It consolidates pen and fill state, drawing order, parameterised subprograms, decomposition and systematic debugging. The checkpoint itself belongs in the Workspace, where your teacher can inspect both code and canvas.

1. Control outline, fill and circle drawing

Pearson's programming subset includes these methods:

artist.pencolor("navy")
artist.pensize(3)
artist.fillcolor("gold")
artist.begin_fill()
# draw one closed boundary here
artist.end_fill()
artist.circle(40)

pencolor controls the outline. fillcolor controls the inside. Filling begins before the boundary and ends after the closed shape has been drawn.

Fill in the blanks3 marks
The method gap 1 changes the outline colour. A filled shape starts with gap 2 and finishes with gap 3.
  • begin_fill()
  • end_fill()
  • fillcolor()
  • pencolor()
  • penup()
Multiple choice1 mark

In standard mode, where is the centre of artist.circle(50) relative to the turtle at the start of the command?

  • A50 units to its right
  • Bat the turtle's current position
  • C50 units to its left
  • Dat the origin
Written answer2 marks

A student sets fillcolor('red'), draws a square, then calls end_fill(). Explain why the square may not fill and state the correction.

Identify the missing state-changing method and where it belongs.

Students type their answer here.

2. Compose in layers

Drawing order and layersLater drawing can cover earlier drawing1 backgroundsky, groundlarge areas first2 objectsbuildings, treesone procedure each3 detailswindows, signsforeground lastpenup → setposition → pendown

Turtle draws immediately. A later filled shape can cover earlier lines, so call background procedures first and foreground detail procedures last. Reposition with the pen up to prevent unintended connecting lines.

Written answer3 marks

A scene contains sky, a house, a tree behind the house, windows and a foreground sign. Propose a sensible drawing order and explain one consequence of choosing the wrong order.

Put large background areas first and details that must remain visible later.

Students type their answer here.

3. Use parameters to compose related objects

Read this code without running it:

def rectangle(width, height, colour):
    artist.fillcolor(colour)
    artist.begin_fill()
    for pair in range(2):
        artist.forward(width)
        artist.right(90)
        artist.forward(height)
        artist.right(90)
    artist.end_fill()

rectangle(120, 70, "blue")
Multiple choice1 mark

How many times does artist.forward(...) run during the call shown?

  • A2
  • B4
  • C3
  • D8
Written answer2 marks

Explain how the parameters and loop make rectangle reusable.

Refer to what can vary and what repeated structure stays the same.

Students type their answer here.

4. Debug from the visible symptom

Useful checks follow the Turtle state:

  1. Wrong location: inspect the latest setposition and whether the pen was lifted.
  2. Wrong direction: inspect cumulative turns or set a known heading with setheading.
  3. Unexpected joining line: check the order of penup, setposition, pendown.
  4. Missing fill: check fillcolor, begin_fill, a closed boundary and end_fill.
  5. Hidden detail: inspect procedure call order.
Written answer2 marks

After drawing the first window, a program moves to the second window and leaves a diagonal line across the wall. Identify the likely cause and give the correction.

Use the pen state before and after repositioning.

Students type their answer here.

5. Plan before constructing

A useful decomposition names visual components that can be built and tested separately. For a park scene, this might be draw_ground, draw_tree(x, y, size), draw_bench(x, y) and draw_sign(x, y, message). The main program then positions and calls those components in layer order.

A strong plan records inputs, visible outcome and test evidence for each component. It does not merely list every Turtle command.

Written answer3 marks

Plan a Turtle scene containing a background, two repeated objects at different positions and one foreground detail. Name at least three subprograms, state useful parameters, and give the call order.

Your plan should be precise enough for another student to begin implementing it.

Students type their answer here.

Written answer2 marks

Describe how you would test and refine one parameterised object procedure before combining it into the full scene.

Include more than one input and say what evidence you would inspect.

Students type their answer here.

Multiple choice1 mark

Which action gives the strongest evidence that a completed Turtle program is working as intended?

  • AThe code contains many commands.
  • BThe code runs once without a syntax error.
  • CEvery object uses the same colour.
  • DEach subprogram and the integrated scene are tested against stated success criteria.

Ready for the practical checkpoint

You are ready to decompose an image, implement reusable subprograms, control drawing state and layers, and show evidence of testing. The practical checkpoint will ask you to demonstrate these skills in the Workspace.