When I was in elementary school, the class was given the assignment to research common sayings such as "Cat Got Your Tongue?" Everyone in the class enjoyed the assignment; my project was to research the phrase "Let's Talk Turkey." This book contains 21 popular sayings with explanations of their origins and their current meanings. For each saying there is a multiple choice problem where the real meaning is one of the selections. The explanation and origin of the phrase then follows the multiple choice question.
This is an excellent resource book for elementary schools. It is a book that children will also read for fun, I used to encourage my children to read such books and then explain some of their readings to me. It made for great mealtime conversation.