Sound

"materials may transmit, absorb, or reflect light sound carries energy
loud sounds carry more energy
forms of sound can be either audible and inaudible
sound is caused by vibrations in a medium
sound can travel through many substances (e.g., air, water, metal)
the shaking (oscillation) of objects is called vibrating
vibrations are measured in the number of oscillations per time (called the frequency)
higher (faster) the frequency corresponds to higher pitch sounds
lower (slower) the frequency corresponds to lower pitch sounds
materials may transmit, reflect, or absorb sound (an echo is reflected sound)
sound travels through gas, liquid, and solids"
Vocabulary: vibration, vocal cords, pitch, frequency, loudness, sound waves, reflect, absorb, transmit, echo
Sources: Mission Hill Elementary School
Changing Sounds interactive from BBC
The World of Science (children's reference book) from Parragon (section 4, page 109)