The Curriculum Standard for Compulsory Education Primary School Science (Grade 3-6) (experimental draft) requires that the learning of primary school science curriculum should be good at guiding students to "scientific inquiry", focusing on exploring the micro-material world and embodying the characteristics of science classroom.
Xiong Guanghua, Hongyun Primary School, Wuhua District, Kunming
Heart target. Through detailed and effective scientific inquiry activities, the unity and implementation of science curriculum objectives can be realized. Aiming at this goal, this paper discusses how to carry out the teaching of scientific inquiry activities in the micro-world in the teaching of the four contents of Unit 1, Book 2 of the science textbook for sixth grade primary school.
First, in the combination of theory and practice, grasp the basic connotation of teaching materials.
The textbook arrangement intention of Section 4-6, Unit 1, Book 2 of the sixth grade science in primary school emphasizes the teaching idea of how teachers lead students to explore the material micro-world in class. According to the requirements of teaching materials, teachers and students cooperate with each other, with the help of naked eyes, magnifying glasses, microscopes, projectors, pictures and so on. To enhance students' knowledge and understanding of the macro-world and micro-world, and further strengthen students' deeper understanding of the biological world. The two are interrelated, which stimulates students to have a stronger interest in learning the mystery and magic of the objective world, and enables students to realize their interest in scientific inquiry and their attitude towards things in the process of scientific inquiry learning. Through the teacher's careful guidance, the students' ability of hands-on, eyes-moving, mouth-moving, brain-thinking and logical thinking has been rationally jumped and improved.
The world is really wonderful. I don't know if I don't see it. The world is big, and there is no wonder. The world around us is a colorful and magical world. From the macro world to the micro world, all kinds of creatures have their own habits, shapes, structures, characteristics and diversity, and all have some similarities. The most obvious feature is that "any living thing is made up of cells". At the same time, it is also the basic unit of organisms. In the past, students' subjective understanding of biology (quality) was based on their initial perceptual knowledge, and their understanding of the biological (quality) world only stayed in a superficial and limited field of understanding.
With the gradual deepening of teaching materials, teachers guide students to observe the structure, shape and appearance of biological cells directly with a microscope on the basis of observing animals and plants correctly with naked eyes and magnifying glasses. Use pictures, language, words and tables to record the cell images, appearance, shape, color, structure and characteristics of organisms observed under magnifying glasses and microscopes. By studying the contents of this chapter and consulting relevant materials, the research results are exchanged, sorted, classified and reported, so that students can gain more new knowledge about cytology and gain effective experience and promotion of emotional attitudes and values in the process of understanding and discussing things. Cultivate students' spirit and skills of learning, loving and applying science, constantly pursuing and being good at pursuing scientific knowledge, broaden their horizons and open up knowledge fields. In the inquiry learning activities in science classroom, students' perceptual knowledge rises to rational knowledge.
Second, in the exploration of classroom teaching, we should pay attention to practice, experiment and actual effect.
In the study of this chapter, the key point is that teachers should carefully guide students to cooperate with each other and * * * cooperate with the realization of classroom goals to achieve a thorough and detailed understanding of the micro-world. First of all, teachers should guide students to practice and think with their brains. Before using a magnifying glass, we should make preparations before class. On the basis of observing biological samples with a magnifying glass, we further learn how to correctly understand the names of microscopes and their components and how to operate microscopes. Through the vivid, intuitive and concrete demonstration, operation and specific guidance of the teacher, students can know the names of various parts of the microscope in detail and master the essentials, processes and precautions of specific operation. Secondly, it is to guide students to understand the content of the textbook, and refer to the pictures, so that students can understand the theoretical basis of "biology is made up of millions of cells in Qian Qian" in detail, so that students' initial perception ability can be further strengthened. Thirdly, under the guidance of teachers, we should mainly do a good job in the process of inquiry activities with observing onion epidermal cells as the main teaching content, specifically observing their internal cell structure and understanding biodiversity as the main content. Explain to students that in order to better observe the structure of biological cells, it is necessary to learn the slicing methods, slicing methods and steps of onion solid specimens, and pay attention to the safety of blades when using, correctly master the use of microscope operating parts, choose eyepiece and objective lens with different multiples to exchange, and adjust the specific side of the knob that can move the stage horizontally or vertically. For example, if students want to observe smaller biological cell bodies under a microscope, they must have certain specific requirements. How to control the focusing spot on the mirror surface of the microscope to achieve the best visual effect? How to place slides correctly? How to adjust the focal length of the microscope lens? How to make the pinhole of microscope objective aim at the specimen accurately? How to change the objective lens? How to correctly adjust the horizontal or vertical movement of the stage? How to adjust the eyepiece slowly and carefully without crushing the glass slide with the eyepiece lens? How to capture the best clear visual image effect of biological cells after amplification under the flashlight of observing specimens? Fourth, teachers need to prepare tools when guiding students to learn onion specimen slicing. When making specimens, teachers should teach students to patiently and carefully scrape off the redundant parts of the object with a blade, and repeatedly scrape them with clean water, so that the thickness of the specimen must be 30 to 50 times that of the object, and the area of the specimen can only be 5 to 15 square millimeter. Then carefully slice the scraped specimen into the "well" box with a blade, and carefully take the middle specimen out of the "well" box with tweezers and put it on a wet glass slide. Fifth, guide students to correctly operate the adjusting microscope for observation. Through the teacher's correct demonstration, operation and guidance, students are gradually guided to observe according to the steps of observing specimens: slicing-loading-adjusting knobs-adjusting slides-adjusting mirrors ... a series of necessities. Observe the structure and appearance of onion epidermal cells with naked eyes and microscope, and ask students to draw the observed onion cells in the record table and describe their characteristics in words. On this basis, guide students to make specimens of other things.
Through several different observation, comparison, re-observation, re-comparison, repeated exploration and comparison, and group cooperation and exchange activities, the teacher finally led the students to sum up the correct conclusion: "Any organism is composed of tiny cells", which enabled the students to have a deeper understanding of the micro-world in their emotional attitudes and values, and stimulated their strong interest in exploring scientific knowledge.
Third, broaden your horizons in the exploration of the micro-world.
Through the above-mentioned classroom learning activities, students observe the appearance, structure, color and other characteristics of biological cells with the help of a microscope. It broadens students' horizons, enables them to further understand the significance of cells to life, and is more interested in discovering more mysteries of the biological world.
In the following teaching activities, our teachers can further expand the classroom content and lead students into the next topic-microbial research and learning. For example, observation and research on human blood cells, human oral epithelial cells, vegetables and food crops cells, other green plant cells, natural water droplets and tiny insects ... enable students to understand some biodiversity and their respective characteristics and expand their cognitive scope.
A green leaf, a drop of blood, a drop of water, a tiny creature, a piece of human epidermal tissue cells obtained in reality, etc. Can be used as a field for teachers to guide students to carry out scientific inquiry.
Through the exploration activities of the whole class, students have further deepened their understanding of microbiology and general biology with the help of magnifying glasses and microscopes. You have seen the structure and characteristics of human blood cells and human epithelial cells. The observed fresh blood cells are round and pink, lifelike and full of vitality, and the arrangement and combination are regular; There are countless tiny microorganisms moving in a drop of water; The legs of small insects are covered with dense bristles; A 5-square-millimeter piece of human skin epithelial tissue has cells with the same size, orderly arrangement, regularity and different shapes in Qian Qian. They are presented in students' field of vision in a colorful way. Make students deeply realize that microorganisms are also creatures, they have the same characteristics as other creatures, and realize that the biological world is diverse, complex and colorful. You can also learn about the relevant content through other channels, such as looking up information and surfing the Internet, so that you can better understand the characteristics of some organisms in the world that are unicellular and some are multicellular.
With the constant use of microscope in class, we guide students to understand and establish the concept of biological cells, and extend it to understand the molecular structure of other microorganisms, viruses, bacteria and other substances in nature, thus initially establishing the concept of biological molecules in students' minds, stimulating their interest in higher-level learning and laying a solid foundation.
In short, before learning this part, the concept of "all living things are made up of cells" is an abstract and vague concept in students' psychology. Through the study of this unit and this chapter, students' horizons are broadened, their interests and hobbies in biology are enhanced, and their understanding of the objective material world is strengthened, thus achieving the learning objectives and tasks of this chapter.
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