Christine Whitcome Good Vibrations Grades 6-8

Transcription

1 TIME ALLOTMENT minute class periods. Depending on your class time, you can make it one or more class periods. OVERVIEW Students will explore various musical instruments and associate the changes in pitch with the structures and sizes of the instruments. Using a computer, software, a microphone, and a data collecting device see the actual frequencies of sound waves produced by their musical instruments. SUBJECT MATTER Physics OBJECTIVES Students will be able to: Demonstrate sound waves and make changes in the waves resulting in changes in pitch Associate changes in pitch in various musical instruments with size and shape and the sound waves they produce STANDARDS National Standards: Physical Science Content Standard B: As a result of their activities in grades 5-8, students should develop an understanding of Properties and changes in properties in matter Motions and forces Transfer of energy State Standards: Investigate and describe the characteristics of waves using such things as ropes, water tables, and springs; describe that waves move at different speeds in different materials, using examples such as sound waves traveling in air as opposed to water; describe the electromagnetic spectrum and how wavelength changes from one end to the other; describe that the energy of waves can be changed into other forms of energy. National Teacher Training Institute / KNPB Channel 5 Reno Good Vibrations...1 of 6

2 MEDIA COMPONENTS Musical recordings featuring instrumental pieces Computer LoggerPro software from Vernier LabPro unit and graphing calculator Microphone to attach to LabPro Web Sites: Login as guest or register. Navigate to the page where you put in the SciLinks code. Use SFS02 for the properties of sound. It will take you to the following links, or you can type in the URL yourself. Sound Waves and Music soundtoc.html This web site contains explanations of sound and musical instrument. There are on-line review quizzes and animations. Introduction to Sound This site requires Windows Media Player which is downloadable from links at this site. This site has interactive sound graphics and links to actual sounds. Music Physics Concepts such as frequency, pitch, resonance are related to music. Longitudinal Waves Activity_page.cfm? This is an interactive site on how sound waves travel through the atmosphere. You will need Shockwave which can be downloaded from a link on this site. This is a copy of an article from Science Scope magazine. It provides very good background information on the science of sound and musical instruments. MATERIALS per cooperative groups of students (3-4 students/group) 8 Glass bottles of the same size (12-16 ounce) water metal spoon 2 straws a fat one and a skinny one 4 rubber bands of varying lengths and thicknesses small box such an empty tissue box 2 pencils wooden ruler tuning forks scissors National Teacher Training Institute / KNPB Channel 5 Reno Good Vibrations...2 of 6

3 PREP FOR TEACHERS INTRODUCTORY : SETTING THE STAGE Gather the necessary materials. Set up five separate activity stations 1. Station #1 Bottle Band Line up the 8 bottles and label them 1 through 7. Bottle #1 will be empty. Gradually fill each bottle with a little more water than you used to fill the one before it. Keep filling until you reach Bottle #8. Bottle #8 should be almost totally filled. 2. Station #2 Straw Flute Cut the end of the straw as shown in the attachment. After cutting the straw, flatten the end with your thumb or a pair of scissors. 3. Station #3 Straw Trombones Cut the end of a skinny straw as you did for Station #2. Insert the skinny straw into a fat straw. 4. Station #4 Desktop Vibrations Place a plastic ruler over the end of the table/desk. 5. Station #5 Tissue Guitar Choose 4 rubber bands of different lengths and thicknesses. Stretch the rubber bands around the tissue box, making sure there is enough room to pluck them individually. Slide a pencil under the rubber bans so they are lifted off the top of the box. Explain to the students that pitch describes how high or low the sound made by a particular instrument will sound to the ears. Also describe that a sound wave is measured by the number or bets or pulses it produces per second. The more pulses, the higher the frequency and the higher the pitch of the sound that is produced. By the same contrast, the slower the frequency of the sound wave, the lower the pitch that is produced. Divide class into five equal groups for work at each station in turn, or have two stations of each type and the groups will be smaller. Students will record their observations as they participate in each of the five stations. STATION #1 BOTTLE BAND Line up the 8 bottles with the varying amounts of water. Using the spoon, tap the middle of each bottle and listen to the pitch that is produced by each to determine how the amount of water in the bottles affects the pitch. National Teacher Training Institute / KNPB Channel 5 Reno Good Vibrations...3 of 6

4 CONTINUED Practice blowing across the top of the bottles to produce a sound. Determine the bottles with the highest to the lowest pitches. (Provide alcohol and cotton balls at the station to disinfect the tops of the bottles.) Record your observations for each part of this activity. Results: When tapping the bottles with the spoon, the bottle with the most water has the lowest pitch and the empty bottle has the highest pitch. The vibration producing the sound is vibrating through the water and the more water, the lower the pitch. When blowing across the bottle, the air in the bottle vibrates and the longer the column of air, the lower the pitch. STATION #2 STRAW FLUTE Once you have cut and flattened the straw, wet the end of the straw and put it an inch inside your mouth. Forcefully blow into the straw. The cut ends should vibrate producing anxious sound. Once you have successfully made sounds with your Straw Flute, use the scissors to cut the straw shorter and shorter as you are blowing into it. This will change the pitch of the sund you are making. Results: As you blow into the cut ends of the straw, they vibrate. This causes the air inside the flute to be compressed and sound comes out the end of the straw. The pitch is proportional to the length of the straw. The shorter the instrument, the higher the pitch. STATION #3 STRAW TROMBONES Once you have prepared the skinny straw and inserted it inside the fat straw, you will make a trombone-type instrument by sliding the fat straw up and down while blowing into the skinny straw. Once you are good at making music with your trombone you can mark the notes on your instrument. Results: Just as with the Straw Flute, the air passing through the cut opening causes the straw to vibrate. This compresses the air inside the straw producing sound waves that come out the other end. The pitch of the instrument is proportional to the length. The longer the instrument, the lower the pitch. National Teacher Training Institute / KNPB Channel 5 Reno Good Vibrations...4 of 6

5 CONTINUED When you added the second straw, you were able to manipulate the length without cutting it as you did in the previous activity. When the fatter straw was all the way, it produced a higher pitch than when it was all the way down. STATION #4 DESKTOP VIBRATIONS Holding the ruler firmly with about 20 cm extending over the desk, snap the ruler so that it vibrates. Move the ruler to the 15 cm mark and snap it again, comparing the sound made during the first time. Listen to the difference in pitch the ruler makes. Try the ruler at the following lengths - 5 cm, 10 cm, 15 cm, 20 cm, and 25 cm. Results: The length of the ruler that vibrated determined the pitch of the sound that was made. When there was a lot of ruler hanging over the edge of the desk the pitch was lower than if there was a short amount of ruler hanging over. STATION #5 TISSUE BOX GUITAR Pluck each of the rubber bands on your Tissue Box Guitar. Listen to the pitch that each produces. Determine whether the thinner or thicker rubber bands produce the higher pitches. Results: The thicker the rubber band, the longer the vibration or sound it will carry. This is why it results in a lower pitch. As the rubber band becomes lengthened or thinner, the pitch goes up. The rubber band vibrates faster because the wavelength was shortened. CULMINATING After discussing the results and the explanations for the results, allow the students to form a classroom band playing their musical instruments and making some Great Vibrations. If available, an excellent way to show the different frequencies of the sound waves is using a computer, a LabPro data collecting device with a graphing calculator, and a microphone. When all connected the LabPro with microphone attached will show the frequencies of the various sounds waves produced. Students will be able to visually distinguish among the various pitches of sound made. National Teacher Training Institute / KNPB Channel 5 Reno Good Vibrations...5 of 6

6 CROSS- CURRICULAR EXTENSIONS Music Lead a discussion about the instruments in a band and an orchestra. Students should now be able to describe why the woodwind section has higher pitched instruments than the brass section. Have students bring in their instruments to demonstrate. A student who will share his/her guitar with the class will make an excellent demonstration of how the strings work. COMMUNITY CONNECTIONS If possible, take students to an elementary classroom to demonstrate and explain the differences in pitch among various musical instruments Attend a concert, classical music is preferred, and listen for the pitches and observe the structures of the various instruments. STUDENT MATERIALS National Teacher Training Institute / KNPB Channel 5 Reno Good Vibrations...6 of 6