Let s Get Loud. The Big Idea. Supplies. Key Prep: What s the Math? Grades 3-5

Transcription

1 The Big Idea Let s Get Loud This week you re making a pan flute out of milkshake straws, then you ll yell into a decibel-meter to find out how loud you really are. Finally, you ll use random items as musical instruments, using math to generate funky rhythms! Supplies Bedtime Math provides: Milkshake straws: 9 per kid Measuring tapes: 1 per kid You provide: Scissors: 1 per kid Markers: 1 per kid Rolls of masking tape for the group Paper or plastic cups: 1 per kid; halffilled with water, to start Safe household items for instruments (trash cans, spoons ): 1-3 per kid Free sound meter app for a smartphone or computer (e.g. Decibel 10 th for iphone) Free keyboard/piano app (for bonus) Key Prep: Count out 8 random-colored straws for each kid. Fill 1 paper or plastic cup for each kid halfway with water. What s the Math? Measuring length Comparing and sequencing lengths Counting, skip-counting Patterns Simple relationships between variables Bedtime Math Foundation. All rights reserved.

2 Kickoff Did you know no one can hear you yell in outer space? That s because there s no air! When we make sound, we re actually rippling the air in waves until it reaches the ear, microphone, or any other sensor that s picking up the signal. Today we re going to test two things about sound: the pitch, how high or low the sound is, and the volume, how loud it is. A Watery Whistle (5 minutes) Intro to the kids: If you ve ever played a xylophone, a guitar or even bottles filled with water, you know that strings or pipes of different lengths play different musical notes. We can see how this works with a milkshake straw and a cup of water. 1. First have everyone take 1 unmarked straw and practice blowing across the top of the straw, rather than through it. 2. Next, each kid puts a straw into their cup half-filled with water. 3. Tell the kids to blow across the top of the straw as they move it up and down in the water. What happens to the sound? Why? Talk about how the length of the straw relates to the pitch low or high. Bonus (optional): Why does this happen? See if they can explain that shorter pieces produce sounds with shorter wavelengths, which are higher in pitch. 4. Have everyone drink or pour out the water in their cups for the next activity! 2

3 Be the Pied Piper (15 minutes) Intro to the kids: Now we re going to use this idea to make our own pan flutes! The pan flute is also called a zampoña (sahm-pone-ya) in South America. 1. Hand each kid 8 straws. 2. Using a measuring tape, each kid measures and marks their 8 straws to the following lengths: o 9 inches o 8 inches o 7 1/8 inches o 6 3/4 inches o 6 inches o 5 3/8 inches o 4 3/4 inches o 4 1/2 inches 3. Kids put an X on the part of each straw below their markings this is the section they will throw out. 4. Then, kids cut each straw at the line they drew, and put their completed flute pieces into their cup to keep track of them. 5. Using masking tape, kids tape over one end of each straw so no air can escape. How does the sound change when you cover one end? Answer: It drops by one octave! 3

4 6. After taping the ends, kids put the straws in order of length from longest to shortest, with the longest on the left. 7. The top open ends should all be lined up. 8. Help kids tape across the straws to hold them together. 9. Now kids blow across the top to make music! How does the sound from the straws change with length? Answer: Shorter straws make higher notes. Bonus (optional): If you have a tuned instrument handy (guitar, keyboard, smartphone app), you can experiment to find out what notes the kids pan flutes play. They can then label the notes on the tape. 4

5 Be Loud (15 minutes) Intro to the kids: Did you know that just as you can measure length and weight, you can measure noise? Sound is measured in decibels. Let s use a sound meter to find out how loud YOU are! 1. Roll out 10 feet on a measuring tape, lock it, and place it on the floor. Kids gather at one end of the 10-foot measuring tape, while you stand at the other. 2. Open up one of the suggested free sound meter apps. 3. The musicians play their flutes one at a time, 10 feet away from your sound meter. Watch and compare the meter readings! 4. Now try voices! Kids take turns standing 10 feet from the meter and talking, while a partner watches the meter to see the range of readings and the peak sound. 5. Then, one volunteer holds a long, loud note on ah at as constant a volume as possible. Everyone watches the meter to see the level. 6. Then the hollerer walks towards the meter while holding that loud note. 7. See if the next yeller can get louder! NOTE: Encourage them not to screech they ll actually be louder if they belt instead. What happened to the decibel reading? Explain that unlike an inch which is always the same amount, decibels change with distance for the same sound: they drop as you stand farther from the noise, and rise as you stand closer. 5

6 Bonus (optional): Can you explain the relationship between distance and decibels? Answers: Sound pressure is inversely proportional to the square of the distance. So if you cut the distance in half, the sound intensity will quadruple. Also note that when you jump 10 decibels, you re doubling the sound, because decibels are logarithmic, not linear. Putting that all together, when you cut the distance in half for any constant sound, the decibels should jump 20 decibels since they re quadrupling, or doubling twice. 6

7 === Grades 3-5 If you have time: STOMP (15-20 minutes) Intro to the kids: In the show Stomp!, musicians use everything from brooms to trash cans to kitchen sinks as musical instruments, which takes lots of math. Let s see if we can Stomp and make our own music! 1. Have each child assemble a wacky instrument using 1-3 household items. 2. Count out loud from 1 to 16, and have everyone beat their instruments on each number. 3. Then, divide into 2 groups (any size is OK). 4. The groups start by playing on alternating beats: one group says birth, then the other says day. They can play along as they say the words. 5. Now do it again, but this time count out loud for them from 1 to 16 again. Have one group play their instruments only on the odd beats (1,3,5 ) and the other group on the even beats (2,4,6 ). Try it again faster! 6. Now count double time! Have the first group say pear, pear, pear while the second group says apple, apple, apple. 7. Once they ve mastered that, the first group plays the beat, while the second plays twice as fast. 8. Try trickier patterns, like skipping every 4 th beat! 9. Then, divide into 3 groups. Get the first two going on even vs. odd, then have the 3 rd group do every beat except the 4 th. 10. Try other patterns, such as quick-quick, slow, slow, slow (apple, pear, pear, pear). Split off additional groups for each new pattern, and see how many groups can play at once successfully! 11. Try marching as a parade while playing. See how far you get! 7