First of all, talk about textbooks.
1, the position and function of this textbook
"Research lens" is the content of the second lesson of Unit 2 in the experimental textbook of the fifth grade of primary school science standard of Jiangsu Education Publishing House. Based on students' existing knowledge of light sources, this lesson guides students to understand the phenomenon of light refraction, to study the characteristics of concave lenses and convex lenses, and to stimulate students' interest in studying more lens problems.
2. Analysis of learning situation
The teaching object of this class is the fifth grade students. Students in this period have average logical thinking ability, but their abstract thinking ability and generalization ability are low, so it is difficult to understand the principles of textbooks. Therefore, students' original theoretical knowledge should be sublimated and transformed into practice in this class.
Second, the teaching objectives:
1, process and method:
Understanding the different characteristics of convex lens and concave lens by comparison method.
2, knowledge and skills:
Knowing that light changes direction when it passes through two different transparent body.
As we all know, concave lenses and convex lenses can change the propagation path of light.
Know the lens characteristics of concave lens and convex lens.
3. Emotions, attitudes and values:
Experiencing human's understanding and utilization of optical laws will bring us a lot of convenience.
Willing to use what you have learned to improve your life.
Recognize that the development of science and technology will bring benefits to human and social development.
The key and difficult point of this course is to let students understand the refraction of light and the different characteristics of concave lens and convex lens.
Teaching tools: lens group, CD-ROM, water, glass, optical bench, light screen, light source, myopia glasses, multimedia projector, courseware, words and pictures, etc.
Three. Oral English teaching methods and learning methods
Teaching methods:
1, guided inquiry, cooperative learning method:
2. Demonstration method
3. Multimedia-assisted method
4. Classroom guidance methods
learning method
1, independent inquiry learning
Step 2 experiment
Step 3: Observe
4. Discuss and summarize.
5. Independent inquiry learning methods
Teaching process:
According to the age characteristics and actual situation of students, I designed the following teaching process with simple scientific inquiry activities as the carrier: scene introduction-organization discussion-hands-on practice-exchange report-data display-expansion inquiry. Starting from the knowledge goal, this lesson is relatively simple and easy to achieve, but in the process of achieving this goal, it is the focus of this lesson to contact life practice and explore skill training.
1, creating a fascinating situation.
At the beginning of this class, I showed the students the goldfish I had prepared in advance and immediately attracted their attention. Then I put the goldfish in another fish tank, and the fish became smaller, which immediately aroused the curiosity of my classmates. Ask students to think about why this phenomenon occurs. Students talk about their own ideas: it has something to do with the shape and material of the fish tank. Then I show pictures to let students know more about the refraction of light and the demonstration diagram of refraction.
2, the main body to participate in hands-on practice
"Inquiry" is an important way of scientific learning in science class. In this part, students are mainly guided to explore the different characteristics of concave-convex lens. Students look at pictures of cameras, glasses, projectors, binoculars and slide projectors and ask: What are the common optical elements of these objects? Guide and inspire students to draw the lens. For students, we can't treat them as a blank sheet of paper. In fact, they have accumulated a lot of life experience. The purpose of teaching is to activate students' original knowledge reserves and bring the fragmented knowledge in students' minds into a relatively complete system. Here, I will arrange for students to observe pictures or other objects on paper with lenses of different shapes. Students found through observation that some lenses can make things bigger, some lenses can make things smaller, and some can't change the size of things. Students are not ignorant of this. They know that a lens that can magnify an object is called a magnifying glass, a lens that can shrink an object is called a reducing mirror, and a lens that keeps an object unchanged is called a flat mirror. At this point, I guided the students to say the concepts of various lenses. Next, I will show a picture of a magnifying glass. Then the teacher struck while the iron was hot: "Who can say the characteristics of a magnifying glass in one sentence?" According to the existing knowledge and experience, students use one word to observe and describe: convex, drum, etc. "What about the miniature mirror?" Students will express their views again: concave, concave and so on. On this basis, the teacher summed up the students' speeches: scientifically, we call magnifying glasses convex lenses and reducing mirrors concave lenses. Then let the students touch with their hands and observe with their glasses. Organize students' messy knowledge and let them know more about concave lenses and convex lenses. On the basis of understanding the concave-convex lens, I led the students to observe the goldfish on the flat glass through a drop of water. The students were surprised to find that the goldfish became bigger and realized that a drop of water was a convex lens. From this, they came to the conclusion that all lenses with thick middle and thin edges were convex lenses, while those with thin middle and thick edges were concave lenses. In this link, students' understanding of concave-convex lens rose from perceptual level to rational level.
Let the students play with the concave-convex lens by themselves and record their group's findings. Students found many things through this link: including the imaging law of concave-convex lens, whether to focus light, etc. Through the demonstration of the teacher's courseware, the purpose is to deepen the students' impression, abstract the parallel light into light with the courseware, reflect the effect of these two lenses on light in the courseware, highlight the focus and focal length, and also show the convergent and divergent images.
3. Negative examples of expansion activities
Through students' discussion, communication, report and hands-on experiment, students have a deeper understanding of concave-convex lens. On the basis of summarizing what the students have learned today, I leave a topic for the students: there are many places worth studying about concave lenses and convex lenses. For example, what happens when concave lenses and convex lenses are put together? Put forward new topics for students, further broaden their thinking and make the discussion develop in depth. Inspire students to further broaden their thinking and make the discussion develop in depth according to the existing information. Please talk about the use of concave-convex mirror in life, which led to the emergence of telescope. Through the demonstration of courseware, the teacher lets the students know the production process and inspires them to imagine more production methods. The whole class exchanged students' works and cultivated students' aesthetic ability.