Puzzles and paradoxes
Many lecturers use puzzles of one kind or another to get students thinking and interested in a topic or to illustrate a principle. Puzzles are often quite easy to turn into multiple-choice questions, so that you can use peer instruction. With a good puzzles, most of the students will get it wrong on their first try. That's a good opportunity to get them to talk to each other and try to convince each other of their answers. You will often find that more students have the right answer after these discussion - students who have got it right are able to explain it to their peers.
Here are a few examples of puzzle questions:
The Four Card Problem
The following well-known problem has often been used by psychologists to study logical reasoning ability:
Claim: Every card with a VOWEL on one side has an EVEN number on the other side
Which cards must you turn over in order to test whether the claim is true?
(A) A only
(B) A and 4 only
(C) A, D and 4 only
(D) A and 7 only
The Ace-in-the-hand puzzle
The following puzzle illustrates the 'or-introduction' rule in logic: from 'A', it follows that 'A or B'.
Only one of the following statements about a particular hand of cards is true:
Is it possible there is an ace in the hand?
A. Yes, it is possible.
B. No, it is impossible.
C. No way to tell from the information provided.