A card machine connects an input, a rule and an output

Record all three parts together when using an add-two paper machine. The output alone cannot explain the transformation, while the paired input and output allow another learner to check whether the rule was followed.

Record the input and output together. A machine rule can be checked only when the original value and transformation remain clear.

Keep the before-and-after values together

Insert a value card. Apply the rule. Record the output.

Input three produces output five under the add-two rule.

The rule must remain consistent.

Can the input be checked from the record? Use counters.

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

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• A decision tree needs a path for every permitted input
• Debug the first wrong state, not just the final destination

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