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Knights and knaves – practice for Years 6–9

Sample questions on Knights and knaves with the right answer and a worked solution, from easy to hard. In the Pickles Academy app a child gets new questions of the same kind every time, so they can't just learn the answers by heart.

Subject
Logic
Year
Years 6–9
Curriculum area
Statements and truth

Question types: Who tells the truth?

Rule: Knights and knaves

A knight always tells the truth, a knave always lies. Suppose one person is a knight and check what follows.

If the guess leads to a contradiction, the opposite is true: that person is a knave.

Example: A: “B is a knave.” B: “We are both knights.” If B told the truth, A would be lying about B: impossible. So B lies, A is a knight.

Watch out: Nobody can say “I am a knave”: a knight would be lying and a knave would be telling the truth.

Sample questions

  1. Question 1 Easy

    On an island live knights, who always tell the truth, and knaves, who always lie. A says: "B is a knight." B says: "A and I are the same kind." Decide whether each statement is true (YES) or not (NO).

    1. A is a knight
    2. B is a knight
    Show the solution
    Answer:
    1. A is a knight – yes
    2. B is a knight – yes

    How it works: The only way nobody breaks their rule: A knight, B knight.

  2. Question 2 Normal

    On an island live knights, who always tell the truth, and knaves, who always lie. A says: "B and I are the same kind." B says: "C is a knight." C says: "A is a knave." Decide whether each statement is true (YES) or not (NO).

    1. A is a knight
    2. B is a knight
    3. C is a knight
    Show the solution
    Answer:
    1. A is a knight – no
    2. B is a knight – yes
    3. C is a knight – yes

    How it works: The only way nobody breaks their rule: A knave, B knight, C knight.

  3. Question 3 Hard

    On an island live knights, who always tell the truth, and knaves, who always lie. A says: "C is a knave." B says: "A and C are different kinds." C says: "All three of us are knights." Decide whether each statement is true (YES) or not (NO).

    1. A is a knight
    2. B is a knight
    3. C is a knight
    Show the solution
    Answer:
    1. A is a knight – yes
    2. B is a knight – yes
    3. C is a knight – no

    How it works: The only way nobody breaks their rule: A knight, B knight, C knave.

Related topics

All Logic topics

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