Two Lies & A Truth

  1. Prepare two false statements about a topic and one true statement.
  2. Read the statements out loud to the students or write them on the board.
  3. Ask the students to  identify the true statement.
  4. Discuss the true statement to determine why it’s true.
  5. Discuss the false statements to determine why they are false.
  6. Ask how the false statements could be re-written to be true.

If you want to turn this into a Main Activity, create and discuss a few examples as a group. Then, put students into pairs or groups and have them create their own. Each group presents their three statements to the class and leads the discussion as listed above.

Example Two Lies & A Truth Question: Right Angles

  1. Right angles are bigger than obtuse angles but smaller than acute angles.
  2. All right angles are congruent
  3. Parallel lines form right angles

Which statement is true?
2. All right angles are congruent. Why is that true? Congruent angles are the same size and degrees. All right angles are 90° so all right angles are congruent.

Which statements are false?
1. Right angles are bigger than obtuse angles but smaller than acute angles. Why is it false? All right angles are 90°. Obtuse angles are larger than 90° and acute angles are smaller than 90°. How could you fix this statement? Just reverse “obtuse” and “acute.”

3. Parallel lines form right angles. Why is it false? Parallel lines never cross. Angles are formed where two lines cross. How could you fix this statement? Rather than Parallel lines, Perpendicular lines form right angles when they cross. 

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