SOUND ENERGY (CONTINUED) Lesson note

PROPOSED LESSON PLAN/NOTE FOR THE TEN WEEK ENDING 18^th NOVEMBER, 2022

2022/2023 ACADEMIC SESSION

SUBJECT: BASIC SCIENCE

TOPIC: SOUND ENERGY (CONTINUED)

CLASS: GRADE 9

NUMBER OF STUDENTS: 16

AVERAGE AGE: 13+ YEARS

GENDER: MIXED

PERIOD: 7^th AND 8^th PERIOD ON TUESDAY AND FRIDAY RESPECTIVELY

TIME: 1:20-2:00

DURATION: 40 MINUTES

DATE: 14/11/2022

SPECIFIC OBJECTIVES: By the end of the lesson the students should be able to;

i. describe reflection of sound;

ii. describe hearing.

 ENTRY BEHAVIOUR: The students are familiar with sounds from human, animals and vehicles.

INSTRUCTIONAL TECHNIQUE: Visual, questions and simulation.

INSTRUCTIONAL MATERIALS: Textbook, lesson note, laptop, projector, marker, whiteboard.

DEVELOPMENT:

STEP I: REFLECTION OF SOUND

   Sound from a vibrating object travels in all medium and spreads in all directions. Like light, sound is also reflected from the surfaces on which it falls. Shining objects like mirrors, metals or hard objects like buildings or stones reflect sound. The phenomenon due to which sound energy on striking some hard surfaces, bounces off in some other direction is called reflection of sound.

   When you stand in front of a high building or a hillock, such that you are at a distance of more than 20 meters and you shout loudly, you will notice that you can hear your own sound other than original sound. This happens due to the reflection of sound from the building. This hearing of reflected sound is called an echo.

   The phenomenon due to which repetition of sound is heard after reflection from a distant hard surface, after the original sound from the given source dies off, is called an echo.

STEP II: HEARING

   Our ear is a kind of device that helps to hear sounds produced around us. You are able to hear what your teacher says in the class with the help of ear. A human ear consists of three parts.

(i) Outer ear or external ear

(ii) Middle ear

(iii) Inner ear

    Outer ear consists of a flap like structure called pinna. It is further connected to the ear canal, at the end of which is a circular membrane, called eardrum (tympanic membrane).

    Sound which enters the outer ear as vibrations hit the eardrum (tympanic membrane) and cause it to start vibrating at the same frequency as that of the sound waves. The louder the sound, the more the movement of the eardrum. The eardrum then transfers this motion to the auditory ossicles (the three small bones in the middle ear) the malleus (hammer), incus (anvil), and stapes (stirrup). The ossicles transfer the vibrations to an oval window in the temporal bone which separates the

middle ear and the inner ear. The inner ear is divided into sections, mainly the vestibule, cochlea and semicircular canals. The cochlea contains the organ of corti which is the receptor organ for hearing and is composed of thousands of hair cells, some of which extend into the cochlea fluid.

    As the cochlea fluid is set in motion, it puts pressure on the membranes of the inner ear, pulling on the tiny hair cells. These hair cells then stimulate nerve cells which are coiled around them. The nerve cells then send impulses to the brain and sound is heard.

EVALUATION: Oral questions

i. Describe reflection of sound.

ii. Describe hearing.

SUMMARY/ CONCLUSSION:

The phenomenon due to which sound energy on striking some hard surfaces, bounces off in some other direction is called reflection of sound. The hearing of reflected sound is called an echo.

ASSIGNMENT:

1. What is reflection of sound?

2. What is an echo?

3. Describe hearing.