Teaching article
A shorter symbol message must still be recoverable
Represent repetition compactly and check that it can be reconstructed.
Five repeated stars can be represented compactly using a count and symbol. Give the decoder the convention and check reconstruction, so the task concerns preserving information rather than merely making the page look shorter.
Five stars can be represented as '5 × star' under the agreed key.
Decode the compressed version back to the original
Include the reconstruction convention alongside the compact message. Shortening a representation is useful only when the intended information can be recovered.
Count repeated symbols. Write count and symbol. Decode the result.
The decoder needs the convention. Is reconstruction exact?
Start with one repeated run.
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 program test case names the starting state and expected result
- Repeat three means three executions in this notation
- A symbol message is readable only with its key
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