Can you recommend a book on what happens at Mass?

I have had the opportunity, every year for the past three years, of instructing a class of 25 children, in preparation for the sacrment of confirmation. I need to teach them about the Mass. Is there anything Catholic Answers knows about, written at a level that confirmation-aged children could understand, that I could give them as a gift after the classes are finished?

Recommended reading:

Mass Appeal by Jimmy Akin