Book excerpt: Your mission is to go back in time and discover the identity of the man who fired the first shot of the American revolution, and bring back his musket. From 1775 to 1781, the thirteen colonies on the North American continent fought a war of independence from England, then the mightiest power in the world. By the rude bridge that arched the flood, Their flag to April's breeze unfurled, Here once the embattled farmers stood, And fired the shot heard round the world. So begins Ralph Waldo Emerson's famous poem "Concord Hymn," sung at the dedication of the Battle Monument in 1837. Even then, the identity of the man who fired the first shot of the war, beginning the Battle of Lexington and Concord, in April 1775, was a mystery. The Time Machine series challenges young readers to use their imagination and decision-making skills to write their own story. Options in the text allow readers to choose any path they like within the plot. Readers must draw on background information about the period to make the right choices. This makes the series a great educational device for youngsters to learn about history and all the different cultures, events, and periods that shaped it.