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Grade 8 · unit review

Review: Compose and Test Boolean Rules

Use truth tables, grouping and counterexamples to check fictional decision policies.

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Bring the unit skills together

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Unit review questions
1. A fictional door requires green badge AND active timer. Badge = true, timer = false. What is the result?
2. Evaluate (A OR B) AND NOT C for A = true, B = false, C = true.
3. For A = true, B = false, what are NOT (A OR B) and (NOT A) AND (NOT B)?
4. Policy: blocked sessions always fail; otherwise token OR pass suffices. Inputs blocked true, token false, pass true produce what?

The download contains your current choices and any checked feedback. Keep the separate transfer-task work in your own document; downloading its instructions does not mark it complete.

Use the skills in a new task

Design a fictional display rule: show a hint only when (request OR demo_mode) AND NOT hidden. Write a truth table for request and demo_mode when hidden is false, then test hidden = true with request = true. Compare the correct rule with request OR (demo_mode AND NOT hidden).

Work on paper or in your own document. Explain the choices you made.

  • List the four request/demo pairs and correct results false, true, true, true when hidden is false.
  • For hidden true and request true, return false under the policy.
  • Show the faulty expression returns true in that case.
  • Give either parenthesized expression or hidden-first pseudocode matching the policy.
Compare with a model response

Rule: (request OR demo_mode) AND NOT hidden. With hidden false, pairs (false,false), (false,true), (true,false), (true,true) give false,true,true,true. With hidden true, request true, demo false: correct result false. Faulty rule gives true OR (false AND false) = true, so it violates the hidden flag. Repair by using the stated grouping, or if hidden return false; else return request OR demo_mode.

A different response can also meet the criteria. Compare the evidence and reasoning, rather than copying the wording.