Reading Metrics
Grade Level
Middle Grades (MG 4-8)
Book Level
8.4
Points
1.0
Fiction/Nonfiction
Nonfiction
Word Count
6993
Points per Word
0.000143
Page Count
72
Points per Page
0.013889
Series
Eyewitness Books
Description
Photographs and text explore such inventions as the wheel, gears, levers, clocks, telephones, and engines.