The five senses—hearing

We hear through movement of the ear drum which is tightly stretched across the ear canal and vibrates when air waves push it.

A lesson plan for grade 2 Science

By Wicky Porch

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Learning outcomes

The students will write a ten minute journal entry about what they have learned about sound vibrations after listening to a lesson and performing a demonstration on sound vibrations.

Teacher planning

Time required for lesson

1 hour

Materials/resources

• can with both ends cut out
• balloon with neck cut off
• two-by-two-inch mirror
• double sided tape
• rubber bands
• strong flashlight

Technology resources

• tape recorder

Pre-activities

• Read books on the five senses.
• Develop concept of vibrations.
• Fun facts about hearing.
• Recording your own voice.
• Listening to musical instruments like bassoon/piccolo for low pitch and high pitch.

Activities

1. Stretch the balloon tightly over one end of the can like a drum and wrap the rubber band around it to secure it.
2. Stick the mirror to the side of the balloon about halfway between the edge and the center.
3. Place the can on its side on a table top with the mirror facing the wall about seven feet away.
4. Tape the can down so it does not move.
5. In a darkened room, point the flashlight at the mirror from an angle to the right.
6. Look at the reflection on the wall.
7. Scream into the open end of the can using different pitches.
8. Watch the spot of light vibrate on the wall.

The sound waves from your vocal chords vibrate the balloon. The tightly packed molecules in the air (high pitch) pushed the balloon outward and the loosely packed ones (low pitch) pulled it back. If the pitch of the screams changed enough, the spot should have vibrated more quickly with the high pitch than with the low pitch.

If there was not much change with the student voices, you may want to try playing some music with a heavy beat. (Rap works well, as does the 1812 Overture by Tchaikovsky.) The spot will juggle rapidly with the high notes and slowly with the low notes, and will make huge jumps with thumps or cannon blasts. The balloon vibrates just as your eardrum does.

Assessment

The students here will write the ten-minute journal entry about what they have observed in the demonstration. The students will be evaluated on their completion of the journal entry.