Emperor Pickletine Rides the Bus: Origami Yoda, Book 6

Several passing references may send readers scurrying to the Internet to learn more about kirigami, the Nakamura Lock, and the Bell X-1. The closing pages include instructions for folding Emperor Pickletine and Flying Darth Vader.

Tommy is especially thoughtful and compassionate. Collaborating on their case file, the kids engage in a terrific back-and-forth that lets everyone have his or her say. Most of the adults are reasonably portrayed -- short-tempered, which is understandable on a trip like this, and a bit strict -- but they have their human sides, too. Mr. Howell punishes the children excessively for fooling around in the museum.

Romance is very much on the tweens' minds. There are several flirtations, and two characters kiss. One student sneaks a cell phone and exchanges texts and selfies with her boyfriend, to the irritation of her friend and seat mate.

There are tons of Star Wars references woven into the story, of course, and a great many brand-name snacks are mentioned, including Fruit Roll-Ups, Wheat Thins, Funyuns, Mountain Dew, Cheetos, Rolos, Hershey's Kisses, and Red Hots. Other brands mentioned include Wendy's, Mini Cooper, and Google.