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Musical Instruments part 2

Developed by W. K. Adams

Students experiment with various sound sources, including voice, cup instruments, string and guitars, to gain an understanding of the connection between sound and vibration

Science Topics
Sound
Sound waves
Vibrations
Resonance
Sympathetic vibration
Frequency

Process Skills
Observing
Scientific inquiry
Comparing
Measuring
Predicting

Grade Level
6-12

Preparation
Complete Part 1 

Set-Up
5 minutes

Activity
45-50 minutes

Clean-Up
5 minutes

Learning Goals
Students will be able to…

describe how string instruments require a source of vibration, a way to change pitch, and a way to amplify the sound
define frequency and vibration in terms of a sound wave and what we hear
describe how vocalizing and music both require a source of vibration, a way to change pitch, and a way to amplify the sounds
describe the difference between resonance and sympathetic vibration

Materials in Kit
Cup instrument

Materials Not in Kit
3 different plastics cups – 1 cup per student group
2 types of string*
Scissors
Damp paper towels

Suggested Optional Materials
Acoustic  & Electric Guitars**

*A smooth/shiny type of string and a rough cotton/twine make good comparisons

**Guitars can be easily accessible to teachers. Try asking the music department in your school or local music stores. Most are perfectly happy to lend instruments for learning experiences.

Set-Up
Gather materials and arrange them so they can be easily distributed to students during class. Each student group should have:

• A 3-foot piece of string
• 1 plastic cup
• 1 paper clip
• Scissors
• Paper towels & water

Introduce the Activity
Divide the students into groups  of 3 0r 4 for the activity and explain that they will be exploring musical instruments by using their voice, string and a cup instrument.

Begin the lesson by introducing the idea of a voice being a musical instrument. Ask the students the following question about the voice:
→How can we feel the movement made by our voices?

If the students struggle to find an answer, ask more leading questions such as:
→Where on our bodies can we feel our voices vibrating?

Students should experiment with this idea for a short period of time. Have them hold their fingers against the front of their throat and say “aaaaaah” to feel the vibrations against their fingers.

Hand out a worksheet to each student

Doing the Activity
Your voice

1. Students will work in small groups to try out different sounds with their voice to answer questions 1-6.

2. Explain that pitch varies when you talk. For example, the last words of a question are at a high pitch than statements.

String Activity

1. To answer 7-8, students will tie a 3-foot piece of string to a table leg and pull it tight. they should try:

plucking it
sliding the string between their thumb and index fingers.

Cup Instrument

To build a cup instrument, students will need to follow these instructions:

a. Carefully poke a small hole in the bottom of the cup with scissors.
b. Thread the string through the hole in the cup and tie it to the paperclip.
c. Pull the string so that the paper clip touches the bottom of the cup.

1. Students will hold the cup so the string is loose and slide the string between their thumb and index finger and answer questions 8-9.

2. Students will attach the string of the cup instrument to a table leg.

a. They will pull the cup so that the string pulls tightly against the table leg and then pluck the string.
b. One partner will hold the string at different lengths, while the other plucks it.
c. After trying a few different lengths, they will answer questions 10-15.

3. For questions 16-17, students will wet their paper towels and pinch the string very tightly as they slide the damp paper towel down the string. If they do it correctly, they’ll hear a very loud sound.

Cup Comparisons

1. Student groups will find at least two other groups that used different cups, but the same string and compare and contrast them for question 18.

2. Now, student groups will find another group that used the same cup, but different string to answer questions 19-20.

3. Students should try to make a sound like a chicken (with quick short slides) and a sound like a while (with long smooth slides)

Electric vs. Acoustic Guitars

1. One group at a time should go up to the guitars to compare them and answer the last 4 questions.

Key Lesson Terminology
Sound wave – vibrations of air molecules that travel through air carrying energy with them

Vibrations – a shaking back and forth movement

Resonance – a natural frequency of vibration determined by the size and shape of an object

Frequency (rate) – wiggles per second (moves back and forth)

Sympathetic vibration – when a vibrating object causes another object to vibrate at the same frequency, which may or may not be a resonance For example, if you place the handle of a vibrating tuning fork onto a table it becomes a soundboard and will vibrate at the same frequency. The table top moves more air than the tuning fork so the sound is louder. A piano string causes the soundboard of a piano to vibrate at the same frequency as the string.

Resonance Chamber – uses resonance to amplify sound

Pitch – how high or low a tone sounds to a person. High frequency sound has a high pitch or tone (treble notes), but low frequency sound has a low/deep pitch or tone (base notes). High sounds are usually above 2000 Hz and low sounds are below 200 Hz.

Modifications
Hard of hearing students can feel vibrations by touching the instruments.

Extensions
Students can keep track of terminology with a vocabulary sheet.

Students who play a stringed instrument can bring their instrument to class to show how the homemade instruments compare.

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