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Musical Pipes Teacher Notes Concepts: (1) Sound is a type of energy produced by a vibration. [6.2.3.1.1] (2) Changing the length (width, tension, etc.) of the vibrating material changes the pitch of the sound produced. [3.2.3.1.1] Questions to get students thinking before the activity or to use after: •What is inside a piano? •Haw are a violin and cello or piccolo and flute or trumpet and trombone alike? How are they different? How are the sounds they produce different? •How do you tune an acoustic guitar? •How does the pitch of a drum change if you tighten the drum head? •What do you hear when you run the mallet down the bars of a xylophone? Materials per group: 2 or 3 lengths of PVC pipes - make sure each student has one pipe - and the pipes within each group are of different lengths (label each pipe with the letter of the note) PVC (½ inch inside diameter) is available at home improvement stores and is easily cut with a hand saw - great place to get your dads involved! two octaves worth of pipes for the whole class to play a song The palm pipes are cut out of ½ PVC pipe to the following lengths. These pipes are set to play anything in the key of F. Note Length (cm) Frequency (Hertz) Note Length (cm) Frequency (Hertz) F 11.8 698 F 23.6 349 G 10.5 748 G 21.0 392 A 9.4 880 A 18.75 440 B♭ 9.2 932 B♭ 17.5 466 C 7.9 1046 (high C) C 15.8 523 (middle C) D 7.0 1174 D 14.0 587 E 6.25 1318 E 12.5 659 F 5.9 1397 Procedure: Introduce this activity with a guitar (or other string instrument) and someone that can play it. Have the musician describe what they are doing while tuning the guitar. This gives you the opportunity to talk about pitch. We describe the frequency of sound with the term pitch. Materials that make more vibrations per second have a higher pitch (like the sounds made by the keys on the right end of a piano) and materials that make fewer vibrations per second have a lower pitch (like what we hear from the keys on the left end of a piano). Depending on your musical ability and the age of your students, you can talk about the numerical frequency of the notes and graph length (independent variable, horizontal axis) vs frequency (dependent variable, vertical axis). The graph is not linear. There are many musical/mathematical relationships that can be discovered and discussed. Pipes that play notes one octave apart have a length ratio of 1:2. Notes that sound good together have length ratios that are small whole numbers. When lined up from shortest pipe to longest pipe students will observe the pitch decreases. Scientific method (controlling variables) extension or revisiting the guitar: What happens to the pitch of the sound produced when a string (wire) is stretched? Have a student pluck a rubber band as you stretch it. Yes, the pitch increases, but is this a fair test? Not really. Too many variables are changing at the same time. The length is increasing along with the tension while the width is decreasing, How would you develop a fair test of the relationship between tension and pitch? Observations/Results: Sounds can be made in many ways. Pipes can be tapped on a hard surface, blowing across one end of the pipe with the bottom open and closed and hitting one end on the palm of a hand. A slightly different pitched sound will be made if the pipe is hit and held on the palm. Students may or may not hear a difference in the sound created by different methods. They may describe loudness, quality and possibly pitch. When comparing the sounds made by different pipes a relationship emerges: The longer the pipe the lower the pitch (frequency) of the sound generated. Summing Up: 1.What is true about the pitch of the short pipes? What is true about the pitch of the longer pipes? Short pipes have higher pitches and longer pipes have lower pitches. 2.Circle the pipe that you expect to produce the sound with the lowest pitch. The longest pipe will have the lowest pitch. 3.Here is a picture of a harp. A harp is played by plucking the strings. Which end of the harp do you expect to play the notes with the highest pitch? Why did you pick your answer? The highest pitch notes will come from the shortest strings. This is the same relationship discovered during the activity. Make sure to play Twinkle, Twinkle, Little Star as a class. Everyone with the note plays as indicated (no matter what octave). Musical Pipes Materials: 2 or 3 different lengths of PVC pipe Procedure: 1. Brainstorm all the ways you could make a sound with a piece of PVC pipe. List the different ways below. Work with one pipe and try out your methods. Name the method and describe the sound you produced. 2. Does one pipe make the same sound no matter how it’s made? 3. Quickly hit one end of the pipe on the palm of your hand. Listen to the pitch of the sound. Use three pipes of different lengths and compare the pitch of the sound. Describe your results in the data table below. Length of pipe Pitch short medium long 4. Find the note written on your pipe. Form a new group with all members having the same note. Are all the pipes that play the same note cut to the same length? 5. Measure the pipes. Listen to the pitch each pipe produces when hit on the palm of your hand. Make a data table to hold the information. 6. As a whole class, line up in order from the shortest pipe to the longest pipe. Play the pipes in order. What do you observe as the pipes are played? Summing Up: 1. What is true about the pitch of the short pipes? What is true about the pitch of the longer pipes? 2. Circle the pipe that you expect to produce the sound with the lowest pitch. 3. Here is a picture of a harp. A harp is played by plucking the strings. Which end of the harp do you expect to play the notes with the highest pitch? Why did you pick your answer? Twinkle, Twinkle, Little Star Melody FF CC DD C little star, how Twinkle, twinkle Harmony C C Melody C Up A A B♭B♭ A C Bf above Harmony A AG Melody C C Like Harmony A Melody B♭ Bf A A G F F G A G a diamond in the sky, A F F C DD C B♭ little star, how Twinkle, twinkle Harmony C C G F wonder what you are. F F E E F AA G G F C A CC G G high, B♭B♭ FF I AA G the world so GG B♭ A A B♭B♭ A G B♭ I G wonder what you are. F F E E F