In Sound, young readers learn energy causes air molecules to move slightly back and forth, causing a sound wave. The energy is passed from molecule to molecule, and the more energy transferred, the bigger the wave and the louder the sound. We hear because the thin, flexible tympanic membrane in the ear picks up the motion of the molecules in the sound wave.
 
Softcover, 8×8 in., 24 pages
Word Count 377,  Lexile Measure 690L
A pronunciation guide is included. Reading Level 1-3, Interest Level 2-5.