Junior High School Physics: Reflection of Light Lesson Notes

Junior High School Physics: Textbook on Reflection of Light

Textbook on Reflection of Light (1)

Textbook Analysis

1. The teaching materials for this course have three major characteristics:

Important content, high teaching requirements, and large teaching capacity

2. Teaching objectives:

1 , Knowledge and Skills

1) Understand that light can be reflected on the surface of some objects.

2) Understand the rules of light reflection and understand the meaning of normal, incident angle, and reflection angle.

3) Understand the reversibility of light path in reflection phenomenon.

4) Understand what specular reflection is and what diffuse reflection is.

2. Process and method

1) Observe the reflection phenomenon of light through experiments.

2) Experience and understand how we see non-luminous objects.

3) Experience and explore the "laws of light reflection" and use experimental methods to obtain the relationship between reflected light, incident light and normal position, and measure the angle between reflected light and normal, incident light and normal , summarize the conclusions of the inquiry, and gain a more comprehensive experience in inquiry activities.

3. Emotional attitudes and values ??

1) Cultivate students’ scientific attitude in the process of exploring "the laws of light reflection"

2) Closely connect with reality , improve the application of science and technology in daily life and social awareness.

3) Encourage students to actively participate in inquiry activities.

4) Cultivation of innovative qualities: Cultivate students’ ability to analyze and solve problems based on phenomena, while also cultivating students’ cooperation abilities.

3. Teaching focus: Explore the reflection laws of light

4. Teaching difficulties: Application of the reflection laws of light in practice, similarities, differences and applications of specular reflection and diffuse reflection.

5. Teaching tools: laser flashlight, white cardboard, plane mirror, toothpicks, homemade courseware

6. Teaching material processing:

In view of the key points of this class, I have reorganized the textbook content. My introduction of concepts and rules is completed through demonstration experiments and student experiments, which is more conducive to cultivating students' observation ability and problem analysis ability.

Teaching method:

In this class, I mainly use the "experimental exploration" teaching method. In the experimental design, the teacher demonstrates the experiment so that students can clearly see the reflected light. The relationship with incident light is important for students to summarize the laws of light reflection. Although errors are inevitable, the accuracy of this experiment is very important because a quantitative angle relationship is to be obtained. Doing this experiment well can lay a favorable foundation for students to summarize the law of reflection. Students demonstrate experiments, allowing students to become the real subjects of the classroom. Comparative experiments are more conducive to students' understanding and memory.

Academic analysis:

Secondary school students are young and have limited experience in inquiry. They are easily attracted by equipment during experiments and abandon the purpose of inquiry, let alone active thinking and active inquiry. . Therefore, I cleverly designed the teaching process to allow students to personally participate in experiments, experience and explore the laws of light reflection, and achieve teaching goals.

Teaching process

1. Introduction of new courses

2. Learning of new courses

3. Summary

4. Feedback exercises

5. Assignment of homework

6. Blackboard design

7. Teaching reflection

1. Introduction of new lessons

There are many ways to introduce new lessons in physics, such as review introduction, small experiment introduction, physics story introduction, etc. According to the knowledge structure of this lesson and the psychological characteristics of the second-grade students, I adopted the introduction method of "experimental phenomena-problems". In the design of this link, I adopted a phenomenon that students are familiar with. When the sun is strong, naughty classmates will use mirrors, watches, etc. to make a bright spot. What is the reason for this? Combining light propagation along a straight line to guide students to observe the direction of light, students can discover this characteristic of light from the light spots on the wall. This leads to the reflection of light.

Use a plane mirror to reflect sunlight. Observe: light spots on the wall and their changes.

2. New course learning

1. Draw concepts from observation

2. Draw rules from experiments

3 , Discover problems by doing

4. Deepen the impression from comparison

1. Get concepts from observation:

In this link, avoid In order to allow students to memorize concepts by rote and draw "one point, two angles, and three lines" from observation phenomena, it is more vivid and direct, which not only activates the classroom atmosphere, but also enables students to change from passive learning to lively and active learning, and cultivates students' observation ability. Demonstrate the reflection of light using a laser flashlight. Have students observe the incident light, reflected light, and point of incidence.

Also use courseware to demonstrate the process.

2. Draw rules from experiments:

Whether students can actively explore and solve problems is the weakest link in current inquiry teaching. The reason is that teachers are used to setting procedures and letting students do them. In this link, I first asked the students to analyze the six nouns "one point, two angles, and three lines". Based on their mathematical knowledge, the students would think of some connections between faces and angles, and the students vaguely formed ideas for exploring the problem. Explore whether the incident ray, reflected ray, and normal are in the same plane? How should we do it? What conditions are needed to prove that the reflected ray and the incident ray are separated on both sides of the normal? What physical quantities need to be verified to prove that the reflection angle is equal to the incident angle. Clarify the general idea of ??the inquiry. Doing so can truly push students to the position of subject and cultivate students' ability to summarize on the basis of observation. This is an important part of cultivating students' exploration ability. At the same time as the demonstration, students can observe the characteristics of special light when the light is 45° or 90° from the horizontal plane.

Demonstration 3: Use a laser flashlight to demonstrate the three laws of light reflection

In order to cultivate students' divergent thinking and careful thinking, and comprehensively analyze and solve problems, I will next After the rules, a method of drawing the reflected light path diagram was designed. Through examples, students can have a further understanding of the law of reflection of light. At the same time, students are given corresponding exercises to train their hands-on ability. Students will have a great sense of accomplishment in the light path diagrams they draw, stimulating their interest in learning physics.

Student exercises: (displayed by courseware)

3. Discover problems by doing:

After learning the law of reflection of light, I then proposed What will happen if the light is incident along the reflected light? At this time, I proposed to let the students demonstrate this process, which not only activated the atmosphere of the classroom, but also enhanced the students' hands-on ability. In order to make physics more relevant to life, students can find similar phenomena from life. If you see a classmate's eyes in a mirror, then a classmate can also see your eyes. At the same time, I also raised the topic of invisible people to let students think about whether it is consistent with scientific principles after class.

Demonstration 4: Reversible light path

4. Deepen the impression from contrast:

Introduce specular reflection and diffuse reflection from here, insert a few vertically on the cardboard The toothpick guides students to imagine that when parallel light hits each incident point, what are the characteristics of the reflected light? Then bend the cardboard at will. At this time, students will find that the normal lines are no longer parallel. Students are guided to imagine that when the incident light is parallel to an incident point, what are the characteristics of the direction of the reflected light? And summarize the similarities and differences between specular reflection and diffuse reflection. Use specular reflection and diffuse reflection to explain phenomena such as blackboard reflection and movie screens using cloth instead of glass.

Demonstration 5: Use mirrors and white paper to reflect sunlight

3. Summary:

Through the above exploration, let students summarize the lessons content, emphasizing the key points and difficulties of this lesson. Through student summaries, the understanding of rules is strengthened, the knowledge learned is consolidated, and students are helped to comprehensively master new knowledge, form a knowledge system, and develop the ability to summarize problems.

Blackboard writing design:

1. Reflection of light: When light is emitted from one medium to the surface of another medium, some of the light is reflected back to the original medium, which is called light. Reflection

2. The law of light reflection:

In the phenomenon of light reflection, reflected light, incident light and normal are all in the same plane; reflected light and incident light are separated Both sides of the normal; the angle of reflection is equal to the angle of incidence. This is the law of reflection of light.

3. The light path is reversible in the reflection phenomenon

4. Specular reflection and diffuse reflection

Teaching reflection

This lesson The basic idea of ??my design is: guide students to ask questions-conjecture-design experiments-conduct experiments-discuss and draw conclusions. In teaching, we attach great importance to integrating theory with practice, and highlight ideas and methods for solving problems. The knowledge of light reflection is closely related to life and natural phenomena. In teaching, we focus on cultivating students' ability to use the knowledge of light reflection to explain phenomena, explain principles, and then solve some practical problems. There are also shortcomings in this class. Due to time and equipment constraints, students cannot fully practice, and students are not allowed to ask questions as much as possible. In future teaching, I will continue to work hard and do better in all aspects.

Textbook on Reflection of Light (2)

1. Textbook Analysis

Physics studies phenomena such as force, heat, light, and electricity. The textbook in this chapter studies the phenomenon of light and its laws, and the exploration of the reflection laws of light is the beginning of optical experiments. Therefore, doing this experiment well also lays the foundation for the subsequent exploration of optical laws.

2. Analysis of Academic Situation:

Eighth-grade students have just come into contact with physics and do not yet have very good experimental inquiry abilities, so the requirements for students’ inquiry process are not too strict. Based on the students' study in the previous section and their existing life experience, students have a little understanding of the reflection of light, but they are still very vague about the specific reflection phenomena and reflection rules. Therefore, this class should encourage students to bravely conduct cooperative exploration and draw conclusions from experiments.

3. Determination of teaching objectives and important and difficult points:

Based on the content of this section and the situation of students, the teaching objectives are now formulated as follows:

1. Through some In life phenomena, we know that reflection phenomena can occur on the surface of objects, we can obtain the reflection rules of light through experiments, and we know that the light path is reversible. Know that reflection includes specular reflection and diffuse reflection. (Knowledge Objective)

2. Be able to draw light path diagrams based on the law of light reflection, and be able to use two types of reflection to explain related phenomena. (Ability goal)

3. Develop a scientific attitude of seeking truth from facts in the process of experimental inquiry. (Emotional value goal)

According to the content and requirements of the textbook, the focus of this section is to use experiments to explore the reflection laws of light. The difficulty is to use the reflection laws of light to make light path diagrams.

IV. Teaching process:

1. Preparation before class:

Distribute equipment before class: a set of light reflection experimenters, laser flashlights (four people a group). The teacher writes the group number on the blackboard in advance and draws the light path diagram for class.

2. Teaching process:

1) Students conduct hands-on experiments and introduce new lessons:

First demonstrate to students: There is a light spot facing the wall. , and then asked the students a question: How to make light spots appear on the wall without shining the light on the wall? At the same time, students are evaluated: Who can do it first? If you can, report your group number. Through evaluation, students' awareness of participation and interest in learning have been stimulated, and good results have been achieved: students have a high degree of participation and are very active in hands-on experiments, which has enlivened the learning atmosphere from the beginning. Then use students’ answers to introduce the topic: reflection of light. At the same time, the teacher appropriately explains what the phenomenon of light reflection is and gives students examples to deepen their understanding of light reflection.

2) Ask questions, students experiment and explore, and draw conclusions: (Key points)

Through reflection from a teacher’s demonstration, ask questions: Through this phenomenon, you can guess: light is What rules are followed during reflection? (Some names should be told to students here so that students can express their conjectures and subsequent experiments) Student conjectures: In order to encourage students to make their own conjectures, teachers do not make any evaluation of students' conjectures.

Before students experiment, they should tell students the requirements for evaluation and some precautions for the experiment. The purpose of adding evaluation here is to allow students to explore and think as much as possible, discover and summarize, and at the same time allow adjacent groups to check each other, which not only reflects the evaluation The fairness of the course also allows students to consolidate the knowledge they have learned. Through the evaluation, it was found that students' awareness of cooperation within the group has increased, as has their sense of competition. At the same time, in order to get more conclusions, some students will read the textbooks, so that the conclusions can be more comprehensive.

After the students experiment, ask the group that has reached the most conclusions to state their conclusions, and the other groups can add to it. In students' experimental conclusions, students may mention that the symmetry point of a point on the reflected light will be found on the incident light; the teacher should guide students to use this conclusion to draw pictures. Some students will say: Since the normal line is artificially drawn, the incident point can be moved and does not always need to be in the same place. Teachers should give affirmation and encouragement in a timely manner. Some groups will say: the reflective surface must be transparent or smooth. The teacher can simply explain the difference between refraction and reflection, and guide students to draw specular reflection and diffuse reflection. During the student experiment, the teacher found that a group's experimental design was very good. He should add an encouragement: This group will face the mirror downward. This way the experiment will make the light very clear and the experimental effect will be very good. Finally, the teacher makes a simple summary, and then clarifies and strengthens the law of light reflection. After the experiment is over, let students put away their equipment. Let students develop good experimental habits.

Followed by a tracking exercise: let 6 students go to the blackboard to make light path diagrams using the reflection laws of light they just learned (also paving the way for the subsequent learning of specular reflection and diffuse reflection), and others Students choose any painting below and complete the following exercises. Students' drawings may not draw normal lines, have two angles that are not equal, have the light arrow missed, or draw the light arrow backwards, so here we will also make an evaluation of the students' drawings. Through evaluation and discussion, the notes on drawing are summarized, so that students can develop good study habits through evaluation: learn to summarize the rules or some issues to pay attention to when doing the questions.

3) Observe the light path diagram and learn two kinds of reflection:

Use the students’ drawings on the blackboard. This picture was drawn on the blackboard before class. It has two purposes: one is Let students use the reflection laws of light they just learned to draw pictures, which consolidates the knowledge of the reflection laws and lays a good foundation for the introduction of the two kinds of reflections later. The teacher connected three or three to induce two kinds of reflection: specular reflection and diffuse reflection. Ask a question: The incident light rays are all parallel, but the reflected light rays are different. Think about the difference between them and what is the root cause of this situation? Then let the students read the books and study on their own and complete the questions in the tutorial plan. Teachers no longer give unified explanations.

4) Group communication, summary:

Through communication between groups, summarize the knowledge learned in this section.

5) Meet the standards in class:

Students answer the title of the tutorial project, and ask the students who do it quickly to write the answers on the blackboard. If they have different opinions, use the color or not. After correcting the writing, the whole class finally discussed and decided on the answer, and then asked the classmates to use red pen to criticize each other. In the end, the team leader counts all those who passed the test in the group and gets a check mark. The final standard evaluation is not only an evaluation of the students' learning in this class but also an overall evaluation of the group. This can drive good students to help weak students and form a good cycle by using students to teach students.

5. Assign homework: Corresponding exercises in the supporting exercise book.

I have finished my lesson. Please criticize and correct any mistakes. Thank you all!

Lecture Notes on Reflection of Light (3)

Dear judges and teachers:

Hello everyone! The content of my class is the fourth lesson "Reflection of Light" in the second part "Light" of the fifth-grade textbook "Science" published by the textbook.

Teaching material analysis

This lesson is divided into two parts: "Illuminating the target" and "Using light reflection". "Reflection of Light" is a continuation of the previous lesson "How Light Spreads", which also studies the propagation characteristics of light. The difference is that this lesson studies what happens when light encounters obstacles during its propagation.

Science classes aim to cultivate students’ scientific literacy and emphasize students’ inquiry-based learning activities. In the first part of the textbook, the activity of "illuminating the target" is arranged, allowing students to experience the experimental process and actively acquire scientific knowledge.

The purpose of learning is not to store knowledge, but to use knowledge to invent and create. The second part of the textbook uses the reflection of light to lead students into familiar life situations and magical scientific exploration activities.

Learning situation analysis

In the previous studies, students already know the light source, shadow and linear propagation of light. Students know that a light source is an object that emits its own light. The moon does not emit light, so it is not a light source. We can see the moon because it reflects sunlight, which lays the foundation for learning this lesson. There are many examples of the application of light reflection in life. Teachers can list these examples to let students recall the phenomenon of reflection and cultivate students' awareness of using scientific knowledge to solve life problems.

Teaching objectives

Through teaching practice, I learned that science should pay special attention to students’ active participation in learning and the cultivation of independent inquiry abilities, and fifth-grade students have unlimited interest in the scientific world. Yearning and fantasy, full of enthusiasm for scientific learning. Based on my understanding of the textbook and specific academic analysis, I set the following goals for this lesson:

Scientific concept

When light hits a mirror, it will change the direction of propagation and be reflected back. , forming the reflection phenomenon of light.

Reflected light also propagates in straight lines.

Scientific Inquiry

Through the entire process of illuminating the goal through inquiry, you will know the steps of inquiry, the main activities involved, and understand the entire process of scientific inquiry.

Make a simple periscope.

Emotional attitudes and values

Understand that the changes in natural things are regular (as long as this law is understood and mastered by humans, then we can apply it to daily life , production and work, helping mankind solve more problems), thereby stimulating students' interest in loving, learning and using science.

Teaching focus: Let students go through the inquiry process and understand what the reflection of light is.

Teaching difficulties: The application of light reflection in life.

Teaching and learning methods

There is a famous saying in the Children's Museum in Washington, USA: When I hear it, I forget it; when I see it, I remember it; and when I see it, I remember it. I did it and I understood. This shows how important the students’ own experiences are. Therefore, I adopted the "guidance-inquiry method", taking students as the learning subjects and allowing them to explore the mysteries of nature on their own like scientists. Since it is difficult for students to complete an inquiry process independently, I also used the group discussion method to allow students to listen to the opinions of group members, which can better cultivate students' cooperation skills and team spirit. Scientific learning should be centered on inquiry. Letting students experience exploration-based learning activities is the main way for students to learn science, and it is also the main learning method of this class.

Preparation of teaching aids and learning aids

Group experimental equipment: flashlight, small mirror, materials for making simple periscope.

Teacher demonstration: pictures and courseware about light reflection.

Teaching procedures

Scientific thinking is the core and soul of scientific inquiry. Focusing on promoting the continuous and in-depth development of students’ thinking, I have designed the following teaching process:

(1 ), setting up doubts to stimulate interest - interest is born at the beginning of class

Based on the students' existing life experience and knowledge base, I asked: In addition to the characteristic of light propagating in a straight line, what other characteristics does light have? Look up and see why the fluorescent lamps in the classroom have lampshades? Why are cars equipped with reflectors? Why should the walls in the classroom be painted white? These are all issues related to light. How to explain them? In this class, let the teacher play a game with everyone. The name of the game is "Illuminating the Target". (The purpose is to prepare the classroom and mobilize students' interest in learning through life problems)

(2), Experimental exploration - the lesson becomes more and more interesting

Happy learning - illuminate the target

(1) Turn on the flashlight and let the light shine on the books on the table from top to bottom. The light is How do you light a book? and draw the path of light.

(2) Without changing the position of the flashlight, stand the book up. At this time, how to let the light of the flashlight shine on the book.

(3) Without changing the position of the flashlight, can we find a way to illuminate the toys in the shadow?

Through group experiments, students’ multiple senses such as mouth, hands, eyes, and brain are mobilized, so that everyone can participate in the inquiry process. During the process of inquiry, students actively think, communicate and cooperate with each other. () After students complete the operation, ask students to talk about how to illuminate the target and what is the propagation route of light. With perceptual knowledge, students also understand what reflection of light is and what happens when light encounters obstacles. Finally, teachers and students jointly summarize the accurate concepts. Thus revealing the subject: reflection of light.

Apply what you learn - using the reflection of light

After the students have experienced the above experiments, they have understood the reflection of light. When the students’ interest has not diminished, they asked: Reflection of light The phenomenon is widely used in life, production, and scientific research. Students, do you know some examples of reflection in life? Provide students with opportunities to think and speak, and extend the classroom beyond class to make students' thinking more active. After the students finish speaking, the teacher can make appropriate supplements, and while speaking, turn on the big screen to display these physical pictures that use the principle of reflection. Then the teacher asked: How do these instruments use the principle of light reflection? Think about it and try to draw the light path diagram of the two examples given in the textbook. Then the teacher completes the reflection principles used in car rear mirrors and doctor's forehead mirrors. Finally, the teacher raised two questions before class:

(1) Why do fluorescent lamps need to be equipped with lampshades?

(2) Why should the classroom walls be painted white?

Scientific Exploration - The Magical Use of Light

When students are still not satisfied with the application of light in life, teachers use courseware to introduce the role of light in scientific measurement to students. Bring students into the mysterious world of science to stimulate students' stronger curiosity and desire for knowledge.

How far away the moon is from us is a difficult problem that cannot be measured with a ruler. When American astronauts landed on the moon in 1969 and 1971, scientists used the principle of light reflection to solve this problem. They placed several special mirrors (laser emitters) on the moon. Scientists on Earth shine light into a mirror, which returns light in the direction of the incident light. Scientists measured the time it takes for light reflection to add to the ground, and then calculated the exact distance to the moon based on the speed of light to be 384,403 kilometers.

When students are still immersed in marveling at the magic of science and the greatness of scientists, teachers encourage students to be good at discovery, thinking, communication, and hands-on creation and invention.

Show a little hand - making a periscope

Now let's make a small craft that uses the principle of reflection - a periscope!

After students use the learning tools to make the periscope, let them talk about how it uses the reflective properties of light.

5. Light pollution

Teacher introduction: Reflection has many useful uses in life, but sometimes it also brings us inconvenience and harm. Have you paid attention? The courseware displays pictures from the textbook. Tell students that glass curtain walls, which are widely used in many buildings, bring a lot of light pollution to people.

Happy Discovery - Pupil Changes

The deskmate shines a flashlight into each other's eyes and carefully observes the changes in the pupils. Then the teacher told the students that the pupil is an organ that can control the incident light. The pupil dilates when the light is weak and shrinks when the light is strong.

(3) Summary of the whole lesson - the lesson is over and the fun still depends on it

Finally, the whole lesson is summarized so that students can have a deeper understanding and memory of the knowledge in this lesson. At the same time, students are encouraged to work hard to learn scientific knowledge, understand more phenomena and laws, and be a thoughtful person in their studies.

In this class, students learn in an atmosphere where I participate, I explore, I discover, and I create, so I am happy. ;