First, the cultivation of physical observation ability
Improving observation ability is the premise and foundation of cultivating and improving thinking ability, and it is an important link to enrich students' knowledge and broaden their horizons. In the physics experiment class, in order to make students develop the habit of observing experiments in a clear-cut, step-by-step and hierarchical manner, teachers are required to adopt different methods and start from several levels when guiding and inspiring students to observe experiments:
1. Observation of physical equipment and instruments
According to the psychological characteristics of junior high school students, teachers can adopt intuitive methods to cultivate the most direct observation ability, such as observing the thermometer wall chart and understanding the structure, minimum scale, scope and use. You can also use comparative observation and characteristic observation to make students distinguish between experimental thermometers, thermometers and thermometers. It is both intuitive and contrasting, and the students are deeply impressed.
2. Observe physical phenomena and processes
It is necessary to be comprehensive and meticulous, and to guide students to see clearly according to the purpose, task and requirements of the experiment. There are many experimental devices to observe the boiling phenomenon of water. The equipment is equipped with thermometer, asbestos net and alcohol lamp, which is easy to distract students' observation. Teachers can guide students to observe a series of details such as the position, quantity, rising speed and volume change of bubbles, and whether the thermometer reading has changed when the bubbles reach the water surface. This requirement narrows the scope of students' observation, which is conducive to reducing the observation time, improving the observation effect, clearly observing the main objectives, and avoiding watching "excitement" aimlessly. Careful and profound observation can improve the quality and ability of observation.
3. Guide students to question in observation and improve the quality of observation.
The improvement of observation ability requires the observer to be good at asking questions in observation, carefully analyze and scrutinize the problems in observation, and find out the correct explanation. For example, in the experiment of "using a rubber rod with fur to attract scraps of paper", some students only noticed that scraps of paper were attracted, while a few students noticed more carefully that scraps of paper jumped down after touching the rubber rod. Teachers can take the opportunity to guide more students to pay attention, make students question themselves, guide them to analyze, find out the reasons, eliminate doubts and fully demonstrate their abilities.
Second, the cultivation of physical thinking ability
Physical thinking ability is the improvement and continuation of students' observation ability, which means that students combine what they have learned with observed phenomena on the basis of observation, understand the essence of problems through abstract activities of the brain, and improve their ability to analyze and solve problems. In order to cultivate students' thinking ability in experiments, teachers are required not only to tell students the experimental principles, instruments, steps and conclusions, but also to inspire students to think correctly, so that students can determine their own instruments and experimental steps according to the principles and complete the whole experimental process independently under the guidance of teachers. We can start from several aspects:
1. Add questions to stimulate thinking.
Teachers can carefully design enlightening questions according to the purpose, principle, equipment and steps of the experiment to guide students to think, or they can ask some questions contrary to their own habits and ideas to arouse students' curiosity. For example, to study the buoyancy experiment, first put the plastic block into a beaker filled with water. No matter how you press the plastic block, the plastic block will eventually float on the water, which leads to the concept of buoyancy. Then, clean the water in the cup, press the plastic block to the bottom of the cup (near the bottom of the cup), and then pour in the water. At this time, ask the students: will the plastic block float? Students must answer that plastic blocks will float, but the experimental results show that plastic blocks will not float. Such "strange" questions can inspire students to think about why, and the teacher takes the opportunity to analyze the causes of buoyancy. Another example is the experiment of boiling water in a paper pot. Ask the students first, will the paper burn out? And tell the students that the paper pot will not burn out, and the students are curious, and then guide the students to analyze and draw a conclusion.
2. Design experiments to guide thinking
Teachers do not write out the experimental principles, equipment and steps mechanically, but leave the design of the experimental process to students, and teachers only play a guiding role. For example, in the experiment of measuring resistance, the teacher can first organize students to review the current law I=U/R and ask students what to do if they want to measure resistance. Students can easily think of R=U/I, measure the voltage across the resistor and the current flowing through the resistor, and then think of using voltmeter and ammeter. This step-by-step guidance can better guide students' thinking development than simply giving a voltmeter and measuring resistance with an ammeter. In addition, students can make their own musical instruments and cultivate their creativity.
3. Improve experiments and promote thinking.
Imperfect experiments can guide students to improve according to their shortcomings. Such as flat mirror imaging. The textbook is demonstrated by two lighted candles, so that the image of one candle coincides with the image of the other candle, and the conclusion that the object is the same as the image is drawn. In the actual experiment, it is difficult to completely "overlap" because of many factors such as the instability of the flame caused by the airflow and the impossibility of completely burning the two candles. I asked the students, how to make "coincidence" more obvious during the experiment? Then some students proposed to use two rectangular wooden blocks with the same size. As a result, the length, width and thickness of rectangular wood blocks obviously overlap, and the conclusion that the image is the same as the real thing is drawn. At this time, I also suggested that the wood block does not emit light and the image is not clear, so it is difficult to find the position of the image. A lighted candle is used in textbooks because it can form a clear image. The students immediately added that the wooden blocks can be wrapped in white paper or bright paper, so that the image will be clearer. This step-by-step inspiration, in-depth layer by layer, promoted the development of students' thinking.
4. Expand experiments and enhance thinking.
Teachers can follow the experiment, expand the breadth and depth of the experiment, increase some expansibility related to the experiment and strengthen the stability of the experiment. For example, in the experiment of measuring the length with a scale, on the basis of measuring the length of textbooks and exercise books with a scale, teachers can flexibly design supplements and ask students to measure the thickness of a piece of paper, the circumference of a coin, the height of a cone, etc., so as to increase the depth and breadth of thinking.
5. Summarize the experiment and deepen the thinking.
After finishing the experiment, the teacher should guide the students to summarize and compare, find out the reasons and analyze the conditions. For example, in the experiment of measuring resistance, compare whether the resistance measured by students with internal connection method and external connection method is the same. Why is it different? Under what circumstances, what methods are used to seek equality? Through analysis and comparison, students can deepen their understanding. In addition, teachers can also ask some questions that can reflect the accuracy of students' knowledge and are closely related to students' experiments, so that students can think and practice after class and process experimental information, so as to achieve the purpose of thinking ability training and develop the thinking teaching function of students' experiments.
Cultivating students' observation ability and thinking ability in experiments is the embodiment of physics teaching reform and an important aspect of implementing quality education. Observation is the basis and premise of thinking, and thinking is the continuation and sublimation of observation. The improvement of observation ability can stimulate students' thinking, develop students' thinking ability and promote the improvement of observation ability, so the two are complementary. Teachers should update their ideas and don't think that students' experiments are just for students to practice. Instead, we should be good at exploring the scientific ideas contained in experiments, carefully designing inspiring experimental schemes, mobilizing students' enthusiasm and initiative, cultivating students' observation and thinking ability while cultivating their hands-on ability, and integrating observation, operation and thinking to make students' experiments play a better teaching effect.