This latest mathematical adventure explores patterning. Matt and Bibi are in Peru so their scientist parents can help decode the patterns on a 500-year-old tunic. All the adventure-loving twins need to hear is that the tunic belonged to the messenger of a never-discovered hidden city, and they are off and running. Riding on guanacos high in the mountains, the only thing Matt can find to keep him warm is the aforementioned tunic. Rather fortuitous, as the patterns on the tunic help them survive pitfalls along the way, while the last two patterns are the key to unlocking the city’s doors. Langdo’s vibrantly colored watercolors support the text, but are not enough to help readers decipher the last pattern. Focusing on repeating, positional and growing patterns, this would benefit from more examples since the story overwhelms the math. A final note provides ideas for activities to practice patterning. Similar flaws mar all the books in this series, this being no exception: lack of adult supervision, disregard for artifacts and the twins’ reliance on pure luck to save the day. All in all a disappointment, although it does fill a gap in the shelf for this concept. (Picture book. 6-9)
