A gypsy girl with a weird dad, a Chinese-American kid with a strange fixation with codes and a kid with a dad who dresses weird. These are the three main protagonists in Henry Clark's excellent novel The Book That Proves Time Travel Happens.
Ambrose' best friend is Tom Xui, an intelligent if slightly overworked kid thanks to his Puma Ma (Tigers aren't native to the US). Together they revel in their zaniness and intelligence. On a fateful trip after hours they meet Frankie, a girl who works in her family's traveling carnival. She has a secret, she knows where a time travel device is but they will have to go to the school's band room because the device is also a musical instrument. They wind up in the nineteenth century and are immediately set upon by slave catchers.
As with any book that involves time travel, some of the loops and goings on are slightly hard to fathom (on their first trip back in time Ambrose gets a call reminding him to save someone) but the historical references are fascinating and show that Clark did his homework. There is a code that the boys use in order to decipher what to do and Clark helpfully included the code so readers can see what it looks like. This I thought was a cool way to introduce Morse Code, something most kids will probably have no clue about.
I myself have often wondered about what life was like in the 70s-I adore the music, the fashion and the vibe of that era-and am slightly jealous of my parents for having lived through it. This book allows the young protagonists to ponder what life would be like and what if anything they can do to influence their destiny. I recommend this book for kids aged 9+. It is a great little read.