Teaching article
A decision tree needs a path for every permitted input
Ensure each permitted case has a defined next step.
List the allowed shapes before tracing the tree. A diagram that handles circles and squares may leave triangles stranded, and the missing branch becomes clearer when the full input set is visible.
To hand: A simple shape decision tree.
- List possible inputs.
- Trace each input.
- Mark uncovered cases.
Trace one example from each allowed category
A tree handling circles and squares needs a response for triangles if they are allowed.
List all permitted input categories before testing the branches. Missing outcomes become easier to see when the input domain is explicit.
Which permitted case is missing? Use a small input set.
Do not assume unlisted inputs vanish.
Resources
- Human Robot Commands – Coding Without Screens Printable Game — Check the command conventions before using the sequence or debugging task.
Further reading
- CS Unplugged — Kidbots and algorithm activities
- Australian Curriculum Version 9 — Technologies overview
Read next
- A shorter symbol message must still be recoverable
- A loop repeats the whole block inside it
- Two-state cards need a shared convention
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