Sound Lessons by 5th Graders

These were our favorite lessons that helped us understand sound.


Lesson #1:


We learned that sound is produced by vibrating objects.

Materials:

Procedures:Do each experiment and write down what you learn.

  1. Strike a tuning fork. While it is still humming put it into a glass of water.
  2. Straighten a bobby pin. Hold it against an inverted empty can while you strum the end of the bobby pin.
  3. Touch your Adam's apple. Then hum a low note.


Lesson #2:

Waves; build a device that generates waves.

Materials:

Procedures:

  1. Fold and cut an index card with 1 cm flaps. Make it just barely wider than adding machine tape, so it feeds through smoothly and evenly.
  2. Open up a slot in the middle by poking a pin along a 2 cm line.
  3. Tape it, flaps down, to another index card with masking tape. Then tape the index card to your table.
  4. Insert about 1/2 meter of adding machine tape into your wave machine. "Vibrate" your pen rapidly back and forth inside the slot while a friend slowly pulls the paper. Make sure they pull slow and steady.
  5. Now doing the same thing make wave trains. Make a short wavelength, long wavelength, and short wavelengths that grow longer.


Lesson #3:

We recorded the vibrating end of a bobby pin as a wave train by streaking it across a greased glass.

Materials:

Procedures:

  1. Open the bobby pin and straighten it. Then fold masking tape over the unrippled end so the tape is perpendicular to the plane of the bobby pin.
  2. Next cut the masking tape into a thin arrow. It should be about 1 cm long.
  3. Take the 2 rubber bands and tightly hold the clothespin to the side of the can. Make sure the clothespin's top is facing the rim of the bottom of the can.
  4. Clamp the "rippled" end of the bobby pin in the mouth of the clothespin.
  5. Now smear some petroleum jelly on the glass microscope slide. Pluck the bobby pin, then lightly skim its vibrating tip across the surface.
  6. Draw the wave train that you see.
  7. How do they change? Do they change?
  8. Try different types of wires. Make your own device to check vibrating waves.


Lesson #4:

How can we measure frequency?

Materials:

Procedures:

  1. Hang a penny on a string. Tape the top of the string to the ruler. Make sure the string to the top of the penny is 24 cm.
  2. What is the frequency of 1 Hertz? To find this out, swing your pendulum. One cycle is when it makes one complete swing from left to right and back to left again. The pendulum ticks like a clock, completing 1 cycle each second. Your penny pendulum is equal to 1 cycle per second. That is one cycle. Notice the swing is similiar to the bobby pin that moved back and forth to produce your wave.
  3. If your pulse beats 72 beats per minute, what is your pulse rate in hertzs? Show your math.
  4. Set up your wave machine with a protective strip of adding machine tape inside. Find your most natural frequency for vibrating the pencil. Speed is not important. Equal cycles is more important so make sure you find a rate that feels comfortable and natural. Make sure you count the same number of cycles over each 10 second interval.
  5. Make a chart that shows your natural frequency. The fields would be: trial; cycles in 10 sec. and frequency (HZ). Then find the average frequency. This is your natural frequency.

    Fill in each trial until you get consistent results. You may have to go past the trials on the sample chart.

Lesson #5:


Sound intensity increases with the amplitude of the vibrating source..

Materials:

Procedures:Do each experiment and write down what you learn.

  1. Touch a vibrating tuning fork to a suspended ping - pong ball while the fork sounds softly
  2. Now touch the ping - pong ball to it when it is loud. What is the difference between the two?
  3. Put a thin masking tape arrow on one prong of the tuning fork so it overlaps about 1.5 cm. Then let the fork vibrate on the greased glass slide. What does the pattern look like?( Try it both loud and soft. Then compare the two.)


Sound