A Sunday school teacher was giving her class the assignment for next week.
"Next Sunday," she said, "we are going to talk about liars, and in preparation for the lesson, I want you all to read the Seventeenth Chapter in the Book of Mark."
The following week at the beginning of the class, the teacher said, "Now all who have prepared for today’s lesson by reading the Seventeenth Chapter of Mark, please come to the front." Half the class stood up and came forward.
"The rest of you may leave," said the teacher, "these students are the ones I want to talk to. There is no Seventeenth Chapter in the Book of Mark!"