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Turtle State Inspector

Run the Turtle State Inspector MicroSim Fullscreen
Edit in the p5.js Editor

About This MicroSim

Students command the turtle but never see what is inside it. This inspector makes the turtle's hidden state visible: x and y position, heading (with a compass dial), pen up/down, and pen color. Each Next Command click executes one turtle command; every state value that just changed is highlighted, so t.right(90) becomes "the heading went from 0° to 270°" instead of a memorized incantation.

Learning objective: The student will be able to predict the turtle's position and heading after each command and demonstrate how heading changes produce shapes.

  • Bloom's Taxonomy (2001): Understand → Apply — interpret, predict, demonstrate
  • Interaction pattern: step-through of a command list with a live state dashboard

How to Use

  1. Pick a program from the dropdown (start with Square).
  2. Before each click, predict: where will the turtle be, and which way will it face?
  3. Click Next Command and check the highlighted values in the dashboard.
  4. Try Pen Demo to see penup() and pendown() leave a gap, and watch the pen color swatch change with t.pencolor("red").

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

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<iframe src="https://dmccreary.github.io/learning-python/sims/turtle-state-inspector/main.html"
        height="512px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

Upper elementary and middle school (ages 10-14), Chapter 5 (Drawing with Turtle Graphics)

Duration

10-15 minutes

Prerequisites

  • Basic turtle commands: forward(), right(), left() (Chapter 5 opening sections)
  • Objects and dot notation (Chapter 4)

Activities

  1. Predict the square (5 min): Step through the Square program. Before each command, students call out the next heading value (0°, 270°, 180°, 90°).
  2. Heading math (4 min): Ask why t.right(90) makes the heading go down by 90. Use the compass dial to verify.
  3. Pen Demo (4 min): Students predict where the drawn line will have a gap before stepping through.

Assessment

  • Student correctly predicts x, y, and heading after any two commands
  • Student can explain the difference between penup() movement and pendown() movement
  • Student can state the four pieces of state the turtle tracks

References

  1. Python turtle — Turtle graphics — official turtle module documentation
  2. p5.js — the JavaScript library used to build this MicroSim