Reading Metrics
Grade Level
Middle Grades (MG 4-8)
Book Level
4.4
Points
0.5
Fiction/Nonfiction
Nonfiction
Word Count
1747
Points per Word
0.000286
Page Count
24
Points per Page
0.020833
Description
This introduction to the human respiratory system explains what it is and how it works, looks at the role of blood in the respiratory system, and discusses why breathing problems occur.