The use of conceptual change texts as class material in the teaching of “sound” in physics

The teacher starts the teaching-learning process by handing out worksheets that include the first step of the conceptual change texts. Subsequently, the students are told to follow the instructions carefully. Since the purpose of this exercise is to diagnose and overcome the misconceptions the students have, it is of the utmost importance that the teacher recommends that the students study individually, not in pairs or in groups with their friends. After distributing the texts, the teacher may ask a volunteer to read the text aloud. Part 4, where the students are required to give examples, and Part 5, where they are encouraged to discuss the subject, will definitely arouse their interest. Additionally, the students will hear what their friends think about the subject matter, and they will all have a chance to correct their friends’ mistakes if any are made. Throughout this period, the teacher must be a guide. He/She must not correct students’ mistakes directly, but encourage them to discover the reasons for their mistakes by offering clues. Finally, by the end of the class, the worksheets must be collected from the students and examined one by one.

Instrument Design

The conceptual change text designed is made up of five parts and has been planned in accordance with the conditions of dissatisfaction, intelligiblity, plausibility and fruitfulness in the conceptual change approach developed by Posner (1982) et al.

It is recommended that students be given those parts separately so that they cannot read the answer in the next part and change their answers accordingly. This will render the teaching more effective.

The texts to be handed out to students must have only texts and figures in boxes. To increase the practical aspect of the exercise, the texts should be produced in two versions, as a “teacher’s copy” and a “student’s copy.” The latter will be the student’s guide. The former will only include the texts containing the knowledge that the students will be taught. While the student’s copy has blank boxes, for example, the blank boxes in the teacher’s copy may be filled with the correct information. Some examples of the student copies of conceptual change texts are presented below, along with information about the particular step of the conceptual change process and what should be done at that stage.

Part 1

The first part of the texts aims to identify any possible misconceptions students may have. This allows a teacher to understand how a student pictures the concept in his/her mind. The primary objective here is to make students aware that they are lacking some of the knowledge required to answer the questions in that part. It is of the utmost importance that the text in use relates to daily life in some way. This helps students to more easily realize what they do not know. This is called “drawing attention,” which is the first part of the dissatisfaction step.

Let's Learn About Sound

While listening to music on the radio, Ayşe turned up the volume to the maximum when she heard her favorite song. Just then, her mother told her to turn it down because she was sleeping next door and was disturbed by the noise. So Ayşe had to turn the volume button back to its old position to turn the volume down. What is this action called in daily life? And, what change in which characteristic of sound does this action relate to?

Please answer the question by explaining your reasons. ………………………………………………………

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Part 2

This part features common misconceptions and answers that are scientifically untrue. In other words, this is the stage where disorder is created within the dissatisfaction step. Students are encouraged to think more deeply about the subject. In this step, students’ minds are caught up in confusion and uncertainty. When they recognize any one of the stated misconceptions as their own, this arouses their curiosity.

The most common misconception about “sound” is that the concepts of “the level of sound” and of “sound intensity” are the same. What about you? What do you think? Now, read the next text very carefully.

Part 3

After students give the problem a second thought, the scientific truths concerning the subject are explained. That explanation must be very clear and intelligible. It must also be backed up with graphs, charts and images, if necessary, because pictures are very effective visual tools that easily grab the student’s attention and make knowledge permanent (Arnheim, 1997).

Let’s see if your answer is correct

When the music is turned down, the intensity of the sound changes. The intensity of sound indicates whether that sound is loud or soft. Intensity is the force of energy flowing through a unit area. Sound intensity is measured on the decibel scale. The further one moves away from the source of sound, the lower the decibel. Intense sound is similar to the sound wave produced by a parakeet, whereas sound at a low decibel is similar to that produced by an eagle (Figure 1 and Figure 2). Sound at high amplitude is known as an “intense sound” whereas sound at low amplitude is called a “dull sound”. “Sound pitch level,” on the other hand, shows whether it is a chirp or a deep vocalization.

While a high level of sound is known as a “high-pitched” or a “high-frequency” sound, a low-level sound is called a “low-pitched” or a “low-frequency” sound. The frequency of a sound depends on the speed of vibration of the sound source. When the sound source vibrates quickly, the pitch level of the sound increases, and so does its pitch. On the other hand, when the sound source vibrates slowly, its frequency decreases, and so does its pitch. Figure 3 shows two sound waves with the same amplitude but different frequency.

Figure 1. Parakeet

It has a high-pitch chirp

Its chirp has a high frequency

Its sound has a shorter wavelength

Its pitch level of sound is high

Figure 2. Eagle

It makes a deep sound

Its sound has a low frequency

Its sound has a longer wavelength

Its pitch level of sound is low

Figure 3. Two sound waves with the same amplitude but different frequency

In everyday life, sound instruments such as hearing aids and megaphones are used to increase the intensity of sound.

Part 4

When students perceive the difference between misconceptions and scientifically true explanations, they are asked to express their own opinions. The aim in this part is to measure how much awareness has been raised among students and see if they still have some question marks in their minds or not. The ultimate goal here is to observe if the students have accepted the new knowledge.

Did you change your mind after reading the text? If you did, please express your views once again considering the text now, and give an example. ………………………………….

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Part 5

In this part, the purpose is to understand whether or not the students have grasped the text well. The teacher draws a conclusion on the basis of the text.

Now, let’s answer the following questions:

I. What is the “intensity of sound?”

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II. What is the “pitch level of sound?”

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III. What type of relation is there between the “frequency of sound” and the “pitch level of sound?”

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IV. Which characteristic of sound explains the fact that dogs can hear the sounds that human beings cannot? Can you give other examples?

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V. Which characteristic of sound can be changed by using a remote control device?

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Below can be found another conceptual change text designed about sound. This one can be offered to students right after the text above is used in class. These two conceptual change texts can be used in two teaching hours (45 minutes each).

Now, let’s read the other text!!

Part 1
Speed of Sound
	Mert joined a high school quiz show. He has to answer the last question right to win first place. Up to the last question, he has performed excellently. However, when the last question is asked, Mert hesitates. The question asked is whether sound travels the fastest through liquids, solids or the atmosphere. What do you think Mert should say?
*Please justify your answer.* …………………………………………………

Part 2
The most common wrong answer to that question is that “Because sound does not meet with an obstacle when traveling through the atmosphere, it moves fastest in the air.” Okay, what is your answer? Now, let’s read the following text.
Part 3
*Let’s see if your answer is correct* Sound waves are known as mechanical waves. To transfer their energy, mechanical waves need atmospheric molecules. That is why they cannot travel in space. Sound waves are made up of objects’ vibration, and in suitable environments like air, water, etc., they travel from one point to another by squeezing in and spreading out. Due to the fact that solids are composed of molecules held together, sound travels through solids much faster. As molecules in liquids are farther away from each other in comparison to solids, sound travels more slowly in liquids. In gases, on the other hand, molecules are the farthest from each other. Therefore, the speed of travel of sound in gases when compared to liquids is even slower (Figure 4). To exemplify, sound travels much faster in a steel pot compared to how it travels through water in a bucket. Furthermore, it travels much faster in water in a bucket than it does in the atmosphere. Sound is created in the atmosphere as air molecules crash into other air molecules in the atmosphere. Some of the energy that creates sound transforms into heat energy when air molecules crash into other air molecules. As a result, as sound moves away from its source, its intensity decreases. solid liquid gas Figure 4.

Part 4
Did you change your mind after reading the text? If you did, explain your views again in the light of the text and give relevant examples. ……………………………………………………………………………………………………..………………………………………
Part 5
*Now, let’s answer the questions below:*

I. How do sound waves travel?

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II. Does sound travel at the same speed in solids, liquids and gases? Why? Why not?

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III. Does sound intensity change as it moves away from its source? Why? Why not?

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IV. Can planting trees in front of our houses contribute to sound insulation? Explain your views please.

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V. Is it possible to hear the sound of a ticking clock in an airtight jar? Why? Why not?

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