MnSTEP Teaching Activity Collection > MnSTEP Activities > Investigation of Pitch & Rate of Vibration

# Investigation of Pitch & Rate of Vibration

#### Summary

This lesson topic is on pitch and rate of vibration. Students will use their prior knowledge about how energy travels in sound waves. The inquiry will be on the investigation of pitch and how the size of the object studied affects the rate of vibration creating pitch.

## Learning Goals

This activity is designed for students to:

1) Observe a demonstration on water bottles being played as instruments with different amounts of water in them

2) Investigate further by experimenting with water bottle liquids, rulers, or straws to determine how size or length of object affects pitch

3) Describe why the size of the object plucked or played is related to the pitch heard

Process skills used in the investigation include: observing, questioning, comparing, and classifying.

Key vocabulary (concepts):

Prior knowledge - wave, crest, trough, distance, sound, and vibrate (vibration)

New knowledge - pitch

## Context for Use

Grade level - 3-5: Groups of 2 or 4
Class size 24-30; Rural Public School Facility
Single Lesson in Chapter of study on Energy

Materials: water bottles (glass if possible), water, food coloring, stiff plastic rulers, straws, scissors, rubber bands, pencil, and science notebook

This activity allows students to investigate how the size of an object is directly related to the pitch it produces when played or struck.

Subject: Physics:Oscillations & Waves
Resource Type: Activities:Lab Activity, Classroom Activity

## Description and Teaching Materials

Introductory Materials:
Water Bottles (glass if possible)
Water
Food Coloring (to help students see water levels better)
Science notebook / pencils

Introductory Activity - Demonstration of water bottle instrument
Begin by displaying a few water bottles with different water levels (use food coloring to show more clearly the difference in water level height). Ask the students what type of sound will be produced by blowing air across the top of the bottleneck. Most students will have probably had some experience and know that a sound should be produced when blowing across the top. Also, ask if they think the water level will have any influence on the sound that is produced. If they think the water level does influence the sound, then ask what type of sound (or pitch) will be produced, high or low. You can have students write their predictions in their science notebook. Then demonstrate for them by blowing across each bottle top. Have students draw the bottles and water levels in their science notebook and also have them record whether the pitch was high or low. Discuss with the students which bottles produced the low pitch sounds (the ones with less water in them) and which created the high pitch sounds (the ones with more water in them). Remind them of our previous lesson with sound waves and review with them that sound is a form of energy that travels in waves. Sound is produced when particles of matter vibrate (or move back and forth quickly). Read textbook page F18 and highlight the second section on high pitch (high frequency sound waves or faster vibrations) and low pitch (low frequency sound waves or slow vibrations). Talk about how the column of air is shorter in the bottles with the most water and the vibration produced is faster resulting in a higher pitch. Then share how the lower pitch sound comes from the bottles with the least amount of water which have a slower vibration being produced. Have students mark the speed of the vibration next to their diagram of the water bottles in their science notebooks. For the next part of the lesson students will try experimenting with pitch on their own.

Pitch Investigation:
Water Bottles (glass if possible)
Water
Food Coloring (to help students see water levels better)
Plastic rulers
Straws
Scissors
Rubber bands
Science notebook / pencils

Pitch Investigation-
After students have participated in the demonstration activity, they are going to investigate further. Students should already have notes in their science notebooks from the pitch demonstration. These can be their observations and prior knowledge notes. Then share with them that they will investigate pitch further with the following choices: water bottles, plastic rulers, and straws. Separate them into partners or small groups (no larger than 4 students in a group) to think of a way they could vary pitch with water bottles, rulers, or straws. Allow some time for them to think in their groups and then have them discuss what they would like to try with the class. You can have the class help brainstorm ideas for those groups having difficulty with what to investigate. Some ideas to try could include the following: other water level heights, empty or full water bottle, objects in the water bottle, rulers plucked at various lengths, straws cut at various lengths, someone holding a ruler or straw while being played, an object blocking the path of the sound produced in the straw or water bottle. Check in with each student group to see what they are going to explore and what materials they will be checking out to use. The should find a place in the room to complete their investigation. If they finish early, they can try another material they haven't investigated (remember the group should only use one material at a time). All data collected should be recorded in the science notebook.

Culminating the Lesson -
After the students have had a chance to complete their investigations gather the students to discuss what results were found. Share results from one material (water bottles, rulers, or straws) investigation at a time. There may be some similar results or new lessons learned from these investigations. Write any conclusions that can be made from what was studied or see if anyone needs to investigate further. This could be done as a full class investigation (teacher lead / students help, or the entire class investigates with the same material). Again, discuss how the length of the object affected the sound. Hopefully students found high pitch sounds coming from and object that had faster vibrations, and low pitch sounds from those with slower vibrations. If time talk about musical instruments, and how the size of the instrument and the way it is played lead to its type of pitch.

References and Resources -

Web sites:

http://nicholasacademy.com/scienceexperiment295oneglassmusical.html - singel water glass experiment

http://www.pbs.org/safarchive/4_class/45_pguides/pguide_804/4484_franklin.html#intro - pbs activities
related to sound & pitch

Books:
Hands-On Science. (by John Graham, Peter Mellett, Jack Challoner, & Sarah Angliss). 2001 Kingfisher Publications.

Jancie VanCleave's 204 Sticky, Gloppy, Wacky, & Wonderful Experiments. 2002 Jossey-Bass.

Houghton Mifflin Science 2007.

## Teaching Notes and Tips

If you have access to instruments in your school, work with your music teacher to see if your class can come and visit for a demonstration of how pitches are created by certain instruments. If time and materials allow, students could create and make own instruments.

## Assessment

Students can be assessed in the follow ways:

1) Notes from science notebook
2) Participation in experiment
3) Sharing of experiment (either posted, shared with the class, or from reading notebook)

## Standards

3.2.3.1.1 - (Energy) - Explain the relationship between the pitch of a sound, rate of vibration of the source and factors that affect pitch.

3.1.1.2.1 - (Practice of Science) - Generate questions that can answered when scientific knowledge is combined with knowledge gained from one's own observations or investigations.