The following is Zhang Chunsheng's teaching documentary and our feelings and experiences about this class.
Teaching process:
1 expert lecture.
Invite technical experts from Taiji Group, the corn processing factory where the school is located, to explain the use of corn to the students.
Expert: The clothes, food, shelter and transportation we apply for in our life are closely related to the corn we are familiar with. First, the clothes we are wearing now are all cotton or chemical fiber, and most of them are extracted from petroleum. The future development trend is to spin with corn starch through chemical synthesis. The clothes we will wear in the future are made of corn. Students can eat our clothes when they are hungry. The students burst out laughing. Secondly, students all know that the main energy-supplying substance of our human body is starch, and many foods we eat contain corn starch, such as ham sausage and some puffed food. Third, we are building a house now. One of the important materials for road construction is cement. In the future, we will use corn starch synthetic material instead of cement as building material, and use corn starch synthetic material as expressway pavement, which is non-slip and wear-resistant. These are all products of corn deep processing. The students are all surprised. Experts explain the use of corn, arouse students' strong interest in learning, and make students curious and yearning for deep processing of corn. )
2 field trips.
Lead students to visit Taiji Group on the spot, listen to technicians to explain the uses and chemical principles of various equipment, as well as the products and uses produced by deep processing, and record the whole visit process.
Students are infected again after seeing various products produced by corn. )
3 material collection, knowledge combing.
Through field visits, interviews, consulting and sorting out relevant materials, students sort out what they have seen and heard and form report materials.
4 Express communication and enhance understanding.
Teacher: Through experts' explanation, on-the-spot visit and consulting materials, students have a new understanding of the comprehensive development and utilization of corn and the utilization of resources and energy in the process of corn production. Let's report and communicate.
(In the first group, students draw the processed corn products into charts, and the students in the group report according to their own learning situation. )
Health: protein can be produced from corn by chemical processing. Protein is a complex compound composed of various amino acids. It is the basic substance of human cells and the main raw material for the body to generate and repair damaged tissues.
Health: Corn can also be processed into vitamin C to participate in various metabolism and enhance the body's resistance.
Health: Glucose can also be produced. Sugar is an important part of food. Glucose is slowly oxidized and converted into carbon dioxide and water under the action of enzymes in human body, releasing energy for physical activities and maintaining body temperature.
Health: There is also ethanol, which can be used for medical disinfection and as fuel. At present, the fuel used in automobiles is ethanol gasoline, which not only alleviates the energy crisis to a certain extent, but also plays an environmental protection role.
Health: Corn cob can be processed into xylitol, corn leaves can be used as textiles, and corn stems and leaves can be used as feed and fuel. So corn is called soft gold.
Teacher: That's a good answer. Which group investigated the corn processing process?
(The second group of students edited the video of the visit and reported the simple process of corn processing on the big screen. )
Health: The main process of corn processing is: corn kernels → soaking tank → grinding → pulping → separation → products.
Health: Physical changes have taken place in the process of soaking and grinding, and chemical changes have taken place in the process of beating, separating and making products.
Health: Soak in sulfur and water when making.
Health: The production process needs a lot of water, and the water used should be called waste water and sewage. These wastewater and sewage will have adverse consequences if they are not treated. My family lives in the corner village near Bohai Group. There is a fish pond in my home. At one time, the wastewater of Taiji Group was discharged without treatment. This kind of wastewater enters the fish pond with the river water, causing a large number of fish deaths and serious economic losses.
Health: My home is near here, and untreated wastewater enters my paddy field, resulting in reduced rice production. Other people's rice yield per mu can reach 1300 ~ 1400 kg, while mine is only about 800 kg, and the price of processed rice in the market is far less than that of others. The color and taste of rice made from this kind of rice are much worse.
Health: My family lives near Taiji Group. In summer, the sewage discharged by the factory has not been treated, and the family are afraid to open the window, because when they open the window, they will smell the unpleasant smell, and they will smell it on the way to school by bike. Now that the sewage from the factory has been treated, we can't smell that unpleasant smell now.
Health: sulfuric acid causes acidification of water quality. We measured the pH value of the water sample, and the result was PH≈2. We can use hydrated lime to reduce the acidity of sewage.
Health: The sewage discharged from the factory also contains protein residue, which will produce an unpleasant smell after rotting. These protein residues will be discharged without treatment, which will also lead to eutrophication of water bodies.
Teacher: So how should we govern?
Health: Extracting protein from wastewater as feed can not only reuse protein in wastewater, but also protect the environment.
Teacher: The student answered very well. Students have personal experience that the days when Taiji Group's wastewater was discharged without treatment did harm to our daily life and production, and also caused pollution to our surrounding environment. Now, Tai Chi Group's wastewater treatment equipment has been put into use, the river near us is getting clearer and clearer, and the surrounding air is getting fresher and fresher, so we can't smell the unpleasant smell any more.
Teacher: Students also know that a lot of fuel is still needed in the production process of the factory. Who has investigated the fuel situation of Taiji Group? Please report.
Health: Bohai Group needs to use a lot of coal in the production process. Under normal circumstances, it burns 180 tons of coal every day. After burning these coals, about 7.2 tons of sulfur dioxide will be discharged into the air. According to this calculation, 2628 tons of sulfur dioxide will be discharged into the air every year. This is not a small number, and it is only a small factory near us. We look up relevant information on the Internet. The world emits10.50 billion tons of sulfur dioxide every year, of which 80% comes from coal burning. A large amount of sulfur dioxide is discharged into the air, which not only pollutes the air, but also produces acid rain. Other members of our group also investigated the harm caused by sulfur dioxide entering the air in large quantities. Let us ask him to report to you.
Health: sulfur dioxide gas will cause harm to human respiratory tract and cause respiratory diseases; When sulfur dioxide is dissolved in rainwater, it will also form acid rain, which will lead to soil acidification, crop reduction or tree death (displaying the collected pictures on the big screen), water pollution (causing fish and shrimp to die) and corrosion of buildings. (Show pictures. )
Teacher: How do the students feel now when they hear the numbers and see the pictures above?
Health: Chemical production consumes a lot of fossil energy. According to the reserves and annual consumption of coal, oil and natural gas in China, coal mining can last 1 12 years, oil can last 10 years and natural gas can last 5 1 year. In other words, when we are about 30 years old, oil will run out.
Health: Chemical production needs to burn a lot of coal, produce a lot of sulfur dioxide, and pollute the air. Chemical production also emits a lot of waste gas, which pollutes our living environment. Therefore, when using fuel, desulfurization should be carried out to reduce the emission of sulfur dioxide into the air, and the waste gas discharged from the factory should be treated and discharged after reaching the standard.
Teacher: OK, you really gained a lot from this activity. Please talk about your feelings.
Health: Through this practical activity, I learned that corn can be processed into many products, such as starch, ethanol, acetic acid, protein and glucose, especially corn fiber and building materials. I didn't expect corn, which we are very familiar with, to have so many uses.
Health: Using the existing resources or energy in nature, we can produce a variety of products through chemical production, which is convenient for our life and improves the quality of life.
Health: I want to learn chemistry well and enrich my knowledge. When I grow up, I want to serve the countryside, improve the rural environment and living conditions, increase crop yield and contribute to building a new socialist countryside.
Teacher: What the students above said is very good. Students also realize that our life is being seriously threatened by lack of resources, energy crisis and environmental pollution. Let's conclude this lesson with one sentence: "Take care of resources, protect the environment, let everyone participate and create a beautiful home together."
Reflection:
1. The integration of chemistry curriculum and comprehensive practical activity curriculum has many advantages in integrating curriculum resources and changing teaching methods. This is an attempt of a new classroom teaching mode and the practice of the concept of curriculum reform.
1 cultivates students' various abilities. The materials and knowledge that students need in the whole activity can be obtained not only with the help of teachers, but also through on-the-spot investigation or consultation, relevant experiments, using relevant books and materials or directly surfing the Internet. These methods are conducive to cultivating students' ability to collect and process information. Students have made clear their responsibilities in personal practice and cultivated the spirit of cooperation and interpersonal skills; At the same time, while students acquire knowledge and skills independently, their awareness and ability of scientific inquiry have also been developed.
2. Significantly change teachers' teaching methods and students' learning methods. Teachers are no longer a single knowledge giver in the teaching process, but more organizers, guides and collaborators in the course implementation. Driven by tasks, teachers stimulate students' curiosity and guide students to experience, explore and discover learning. Teachers are no longer the "protagonists" in teaching, but go behind the scenes and become "directors", learning and growing with students in practical activities. The change of learning style makes students become the masters of learning, endows students with a sense of social responsibility, stimulates students' interest in learning and their sense of participation, and makes students happy and free to study and have fun in middle school science.
3. Promote the professional development of chemistry teachers. The integration of chemistry course and comprehensive practice course makes the course content very social and practical, and the subject knowledge permeates each other, far beyond the scope of teaching materials. When integrating curriculum resources, teachers should not only be familiar with textbooks and master Curriculum Standards, but also collect and process all kinds of information. This process forces teachers to constantly update their professional knowledge, broaden their knowledge, pay attention to the accumulation of usual materials, gradually learn to deal with various new situations, master the skills and methods to deal with various problems, and improve their ability to analyze and solve problems.
Second, several problems that teachers should pay attention to in teaching implementation
1 teachers should seriously study the Curriculum Standards and textbooks, and establish the subjects to be integrated according to students' basic knowledge, hobbies, community background and natural conditions.
Teachers should carefully plan and arrange the content of the whole activity, carefully organize the implementation of the activity, and give guidance and supervision in a targeted manner so that the activity can be carried out normally.
Teachers need to pay attention to and protect students' enthusiasm, communicate with parents at the same time, and win the understanding and support of parents and society. Make full use of chemical resources in students' lives, organically integrate chemistry courses with comprehensive practice courses, and collect materials through expert explanations, field visits, online visits, etc. Classroom communication, design experiments, induction and summary and other learning methods create an independent, cooperative and exploratory learning atmosphere for students, so that students can experience the chemistry of life and cultivate their problem consciousness and exploration spirit.
Editor Zhang Ye