Tick-Tock!

**What time is it . . . and how do you know?

This fact- and photo-filled Smithsonian Penguin Young Reader will fill you in on how people first began measuring time and why knowing "when" is important.**

Time is when things happen and how long they take to happen--but how long is all that? The history of telling time is the history of inventions and communication, from hour glasses to atomic clocks, from calendars to chronometers. Tick-Tock is a fun look at the many ways different people have tried to get in sync.