Painless Junior: Grammar (Barron's Painless Junior Series)
(back cover):Honest, kids! . . .  It's fun to learn. . .Enter Grammar World, a make-believe amusement park where kids are introduced to animals who describe different kinds of sentences . . . then take rides and learn about parts of speech . . . and later go on to visit a water park, see a dolphin show, and enjoy a fireworks display. All of these fun events teach you something new about grammar!