The original of the sixth lesson "Bat and Radar" in the first volume of the fourth grade of primary school.
There are two bright spots in the clear night sky. When we get close, we can clearly see that there are two lights, one is red and the other is green. Then there was a rumble. This is an airplane that flies at night. How to fly safely in the dark? It turns out that people get their inspiration from bats.
Bats fly at night and can catch moths and mosquitoes; And no matter how you fly, you have never seen it collide with anything. Even very thin wires can be cleverly avoided. Are your eyes so keen that you can see everything in the dark night?
In order to find out this problem, scientists did an experiment more than 100 years ago. In a room, a lot of ropes were pulled at will, and many bells were tied to the ropes. They blindfolded the bat and let it fly in the house. The bat flew for hours, but no bell rang. It didn't touch any rope.
Scientists have done two more experiments: one is to plug the bat's ears, and the other is to seal the bat's mouth and let it fly in the house. Bats bump around like headless flies, and the bells hanging on the rope keep ringing.
Three different experiments have proved that bats use their mouths and ears to find their way at night instead of their eyes.
After repeated research, scientists finally uncovered the secret that bats can fly at night. When it flies, it will make a sound from its mouth. This sound is called ultrasound. Human ears can't hear, but bats can hear. The ultrasonic wave moves forward like a wave, and when it meets an obstacle, it reflects back and reaches the bat's ear. The bat immediately changes its flight direction.
Scientists imitated the bat's method of exploring the road and fitted the plane with radar. The radar sends out radio waves through the antenna. When the radio waves meet obstacles, they are reflected back and displayed on the screen. From the radar screen, the pilot can clearly see whether there are obstacles ahead, so the plane is safer to fly.
The lesson plan of "Bat and Radar" in the sixth lesson of Chinese in the fourth grade of primary school is two parts.
Teaching objectives 1. Know the new words 13 (including 1 polyphonic words) such as "Bat, Bat, Qi" in this lesson, and write the new words 14 such as "Da, Mosquito, namely" to understand the meaning of related words.
2. Read the text aloud, master the main contents of the text and understand the characteristics of bats flying at night.
3. Find out the conclusions of three experiments, cooperate and exchange what inspiration people get from bats, and understand the relationship between safe flight at night and bat exploration; Inspire the interest in science from an early age and cultivate the sense of innovation.
Teaching focus
1. Grasp the key sentences and learn how scientists get inspiration from bats.
2. Stimulate the interest of loving science and being willing to observe and explore, and broaden your horizons.
Teaching difficulties
1. Find out the respective pathfinding principles of bats and radars, and the relationship between them.
2. Have a preliminary understanding of what bionics is and understand the application of bionics in life.
Class arrangement
2 class hours
first kind
Teaching objectives
1. Know the new words 13 (including 1 polyphonic words) such as "Bat, Bat, Qi" in this lesson, and write the new words 14.
2. Understand the meaning of keywords and learn to summarize the main contents of the text.
3. Know what radar is and the basic knowledge of bionics.
Teaching focus
1. Learn to create new words and write correctly.
2. Understand the main content of the text.
Teaching process:
First, introduce new lessons and reveal topics.
1. The teacher wrote the words "bat" and "radar" on the blackboard, and showed the pictures of bat and radar in multimedia.
2. The teacher adds the word "he" between "bat" and "radar" to guide students to understand the topic.
Clarity: The title uses a word "and" to connect bat and radar, which is intended to let us explore the relationship between them.
3. Introduce bats, radar and bionics.
Bats are mammals with real flying ability, living in caves of various sizes, gaps in ancient buildings, ceilings, partitions, tree holes and rock gaps in mountains. Most bats rest during the day and eat at night. Bats mainly use ultrasonic echo location to search for food, detect distance, determine targets, avoid obstacles and avoid enemies. It emits ultrasonic waves with a frequency higher than 20000 Hz from its mouth. This kind of sound wave is inaudible to human ears, but can be heard by bat ears. Ultrasonic waves will reflect back when they encounter obstacles and reach the ears of bats. Bats can judge the appearance and position of obstacles through their brains.
Radar is a device that uses electromagnetic waves to detect. The radar emits electromagnetic waves, and then the receiver receives the reflected electromagnetic waves. The received electromagnetic wave can be reflected on the indicator to display the image of the detected target, so that the direction, distance and size of the target can be determined. The main application fields of radar are military operational command and civil navigation guidance.
Bionics is a science that imitates biological special skills, mainly observing, studying and simulating various special skills of natural organisms, including structure, principle, behavior, various organ functions, physical and chemical processes in the body, energy supply, memory and transmission. , thus providing new design ideas, working principles and system architecture for science and technology.
Second, read the text for the first time and check the preview.
1. Teachers guide students to read freely. Thinking about courseware presentation: Scientists get inspiration from _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
2. Students can read the text freely, read the correct pronunciation, read the sentences and circle the new words.
3. Teachers instruct students to check each other's memory of new words.
4. The teacher previews the words.
A word card with pinyin is displayed in the courseware, and it is named reading. The teacher's camera guides students to pronounce new words.
Handwritten words: radar (dá) mosquito (wén) son (jí) makes scientific scientists (kē) horizontal (hénɡ) seven vertical (shù) eight ropes (shénɡ) son (jì) catch flies (yínɡ).
Recognizable words: bat (biā n) bat (fú) open (q ǐ) show keeness (ru ǐ) bell (dā n ɡ) open (ji ē) obstacle (zhànɡ) obstacle (yínɡ) screen (pínɡ
Third, read the text again and feel it as a whole.
1. Guide the students to read the text again and circle the difficult words and sentences.
2. Share the circle painting content at the same table, and the teacher will dial out keywords according to the students' communication.
(1) How to fly safely at night?
Presupposition: first, guide students to understand that "black" is a state word and a polysemous word, and then show pictures of black hair and a cave without light respectively, so that students can understand that "black" refers to a very black color in the previous pictures; In the latter picture, "dark" means very dark and there is no light. Finally, combined with this sentence in the article, we can see that "darkness" should be the second meaning here.
(2) Is it special (keen) to see everything clearly in the dark night?
Default: "keen" means sensitive (feeling) and sharp (eyes). When explaining this word, teachers can show its synonym "agile" and antonym "slow", so that students can perceive its meaning through words with similar or opposite meanings, thus deepening their impression.
(3) A room has a lot of ropes tied with bells.
Preset: Show the room map with articles piled up at will and the neatly arranged room map, so that students can feel the meaning of "littering" in comparison.
When it flies, it makes a sound from its mouth. This sound is called (ultrasound). Human ears can't hear, but bats can hear.
Hypothesis: Ultrasound may be unfamiliar to students. Teachers can combine the application of ultrasound in life, introduce the knowledge about ultrasound appropriately, and guide students to understand its meaning.
One kind of ultrasonic wave is sound wave with frequency higher than 20000 Hz, which can't be heard by human ears. Like sound waves, it is produced by the vibration of matter and can only propagate in the medium; At the same time, it also exists widely in nature. Many animals can emit and receive ultrasonic waves, among which bats are the most prominent. It can fly in the dark and catch food with weak ultrasonic echoes.
3. Classification of guiding words.
◆ Onomatopoeic words: rumbling, chirping, gurgling and croaking.
Numbers: colorful, upside down, shouting, drinking 60 thousand, 15 10.
4. Grasp the content of the text as a whole.
(1) Guide students to read the text silently, and show the problems to be considered in silent reading.
Reading and thinking:
A. what is the core content of this article? People are inspired by the fact that bats can fly at night and install radar on airplanes.
B. What do bats do to find their way at night? How did scientists find out? (mouth and ears; Three experiments)
C. how do scientists experiment? What is the final conclusion? Blindfold your eyes, don't ring the bell, plug your ears and seal your mouth, everywhere; Bats fly at night not with their eyes but with their mouths and ears.
D. Why can bats fly smoothly at night? When a bat flies, it sends out ultrasonic waves from its mouth, and when it meets obstacles, the ultrasonic waves reflect back, and the bat receives the echo, so as to locate it.
Presupposition: Guide students to read the text by themselves and extract key information from the text to answer.
Show the courseware and fill in the blanks by naming the students: Bats fly at night by _ _ _ _ _ _ _ _. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Inspired by this, scientists put _ _ _ _ on the plane, thus making flying at night safer.
(2) Group cooperation and communication, divide the text into levels and write the main contents of each level.
A. number the paragraphs and divide them into levels.
B. sort out the main contents of each layer.
The first part (1~2): It is inspired by bats to write that airplanes can fly safely at night.
The second part (paragraphs 3-7): Scientists discovered the mystery of bat flight through repeated experiments.
The third part (the eighth paragraph): write that the plane can fly safely at night by radar.
Fourth, classroom review, exchange gains.
1. The teacher summed up the teaching content of this class and commented on the students' classroom performance.
Transition: We know that even in the dark night, the plane can fly safely and smoothly, because people get inspiration from bats and equip the plane with radar. So how do people get inspiration from bats? What is the special function of radar, which can effectively command aircraft to avoid obstacles? Let's discuss it in depth next class.
Summary: In today's class, we started with new words, mastered the rules of pronunciation and keyword writing, and understood the meaning of keywords. With the joint efforts of all of us, we have also grasped the main contents of the text as a whole. There are so many knowledge points that you must master them, so you must review them more after class, and the teacher will check them next class. In this class, the students are doing very well. It is not easy to sum up the laws of literacy according to the teacher's explanation. _ _ _ _ Before class, I learned about bionics and ultrasound by consulting materials, which is helpful to understand the content of the text; _ _ _ _ _ has his own views on the text, _ _ _ _ _ _ _
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2. Guide students to exchange gains.
(1) communicate freely and accumulate learning methods.
(2) Ask relevant questions in the process of previewing the text and try to give answers.
Example of problem
A. What is the function of the second paragraph of the text?
Do bats fly by their eyes at night?
C. how do scientists study the flying principle of bats?
D. what is the secret of bats flying at night? How does it distinguish obstacles?
E. What is the relationship between bats and radar? How can scientists make use of this relationship?
……
Five, homework design, consolidate and improve.
Complete the corresponding training in this lesson.
Second lesson
Teaching objectives:
1. Grasp the key sentences and learn how bats fly at night.
2. Summarize and analyze several experiments made by scientists, and grasp the enlightenment that scientists get from them.
3. Understand the relationship between bats and radar, and understand the working principle of radar.
4. Understand the application of bionics in life and stimulate the interest in exploring science.
Teaching focus:
1. Grasp the process that scientists get inspiration from bats to install radar on airplanes.
2. Be brave in exploring in life and cultivate innovative consciousness.
Teaching process:
First, review old knowledge and introduce new lessons.
1. Teachers read words, students write dictation, and teachers check students' dictation.
Radar moths and mosquitoes, even if they are smart and sensitive, tie their shoelaces scientifically, and research on fly prevention promotes imitating antenna radio waves to drivers.
2. Guide students to speak enthusiastically and talk about the main contents of the text.
Clear: This paper mainly tells that scientists have uncovered the secret that bats can fly at night through repeated research, and gained inspiration from it, and installed radar on the plane to solve the problem of flight safety at night.
3. Teachers transition and introduce new courses.
Transition: After previewing the last lesson, we have mastered the content of the text and know that people install radar on the plane to make the plane fly safely at night, which is inspired by bats. So how did this inspiration come from? Now let's go into the text again and explore with scientists.
Second, study the text, focusing on exploration.
1. Guide the students to read the text again, and circle the key contents and incomprehensible sentences while reading.
2. Communicate with each other at the same table and talk about the understanding and doubts about the content of the circle painting.
3. Call the students to report, and the teacher asks the representative questions with a camera.
How do planes fly safely in the dark? It turns out that people get their inspiration from bats. (What rhetorical devices are used in these two sentences? What is the role in this article? Do you have any questions after reading these two sentences? )
Presupposition: Guide students to recall common figures of speech, and make it clear that these two sentences use rhetorical questions. When analyzing the functions of these two sentences, students can be guided to combine the context. Students can have different opinions on the question after reading the sentence, and the teacher should encourage them as long as they are reasonable.
Methods: The rhetorical devices include metaphor, personification, parallelism, duality, exaggeration, quotation, rhetorical question, intertextuality, synaesthesia, irony and repetition. Asking questions is one of them, which is often used to express emphasis. In order to emphasize a certain part of the content, deliberately ask questions first, know perfectly well past ask, ask yourself and answer yourself. Correct use of problems can attract people's attention and inspire thinking; Highlighting certain contents makes the article make waves and change a lot. Questions should be used appropriately, that is, where necessary, when necessary, targeted and enlightening.
(2) Bats can also catch moths and mosquitoes by flying at night; And no matter how you fly, you have never seen it collide with anything. Even very thin wires can be cleverly avoided. (This sentence uses several related words. What is the expression effect? Can you write another sentence with these related words? )
Presupposition: first, guide students to find out the related words used in sentences, and then analyze their expression effects in combination with sentences. When writing sentences with these related words, students should be reminded to pay attention to the logical relationship inside the sentences, which can actually make sense.
(3) Scientists discovered the secret that bats can fly at night through research. After repeated research, scientists finally uncovered the secret that bats can fly at night. Comparing these two sentences, what do you find? What do you feel from it? )
Presupposition: Guide students to read the sentences repeatedly, find out the differences between the two sentences in terms of words (the second sentence uses the words "repeatedly" and "finally"), and then experience the expression effect of using these two words (showing the hardships of scientists' work).
When it flies, it makes a sound from its mouth. This sound is called ultrasound. Human ears can't hear, but bats can hear. The ultrasonic wave moves forward like a wave, and when it meets an obstacle, it reflects back and reaches the bat's ear. The bat immediately changes its flight direction. These words reveal the mystery of bats' nocturnal behavior. Can you say it in your own words and draw a schematic diagram? )
Default: The teacher shows the schematic diagram, and then explains the schematic diagram in detail with sentences. The combination of pictures and texts will make it easier for students to understand.
Example of schematic diagram: bat mouth → > & gt& gt (ultrasonic)
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