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Interactive
Georgia State University

Georgia State University: Hyper Physics: Speed of Sound

For Students 9th - 10th
Physics tutorial on measuring the speed of sound in dry air. An interactive form allows the student to practice solving problems involving the temperature dependence of the speed of sound.
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Lesson Plan
PBS

Pbs Teachers: Scientific American: Expedition Panama: Echoes in the Night

For Teachers 9th - 10th
Explore your prior knowledge about bats and investigate bats' use of echolocation to identify and catch prey. Design a game like "Marco Polo" to demonstrate echolocation.