While it has been easy to discriminate sounds, third graders are now trying to uncover what actually causes sound.  With a few "instruments," third graders are gathering evidence for what causes sound and also what causes the sounds to be so different from each other!

Did they see something happen when the struck the tuning fork?  Did they feel something?  What about with the long gong made of string, a cup, and a metal hanger?  Did they see or feel something when they heard the pencil strike the hanger?  

Every sound we hear can be discriminated against another sound. For example, the sound a washer makes sounds quite differently than the sound a popsicle stick makes.

Knowing that sound can be used to communicate, third graders are using sound to "tell" a code.  Using their drop chambers and some everyday objects, they are trying to have their friends guess their secret message.  Their sound code is one example of a code.  We discussed how braille, sign language, and music are special codes, too!

How can you tell sounds apart from one another?  Do they all sound the same?  Or are you able to hear the differences?

Acoustical engineers must be able to discriminate sounds apart from one another, especially as we want to be able to hear specific sounds and not others.  Third graders began their sound unit trying to discriminate sounds playing the Drop Challenge!  They had to try to match the sounds their friends made from dropping everyday objects.  For example, when you drop an eraser and a washer, they make very distinguishable sounds!  

Kwame is a young boy living in Ghana.  Even though Kwame is blind, he doesn't let this get in his way of performing in his village's music festival.  Determined to learn about sound, Kwame seeks the help of an acoustical engineer.

Learning about how to discriminate different sounds, Kwame becomes an acoustical engineer himself!

Key Vocabulary:  acoustical engineer, sound, energy, pitch, frequency, volume, amplitude, source, receiver, vibration, spectrogram, property, tension, medium, amplify, and damp.