The second practice: students improve their ability to solve problems independently in the process of inquiry

The third practice: teachers guide in time, and students' inquiry consciousness is enhanced.

The first method: let students have experience and understanding in the process of inquiry.

Teaching philosophy:

In the usual teaching, students have done experiments to measure the power of small light bulbs. By measuring the voltage at both ends of the small bulb and the current passing through it, the power of the small bulb can be obtained according to the mathematical relationship of electric power. In teaching, the teacher puts forward three questions. According to the teacher's questions, students design an experimental scheme to measure the power of small light bulbs through group discussion, so that students can make connections in computer simulation electrical experiments. Demonstrate the operation process. Especially the connection of sliding rheostat is the weakness of students. At this time, the connection and dynamic change can be solved intuitively in the analog electrical experiment. In addition, the connection of "+"and "-"terminals of ammeter and voltmeter and the selection of measuring range can have a correct operation process. Students conduct experiments, collect useful data, and measure the power of small light bulbs through calculation. Students have been effectively trained in the experimental operation.

Teaching reflection:

After the first practice, the teaching and research group carried out teaching and research activities and reflected under the guidance of the district teaching and research staff. It is considered that the three problems are designed, connected, collected and solved by operation at the same time, with large content, insufficient slope, not deep exploration and not deep impression on students. In addition, students' enthusiasm for participating in experiments is insufficient, and the problems reflected in practical operation can not be effectively solved.

The second practice: students improve their ability to solve problems independently in the process of inquiry activities.

Teaching philosophy:

In view of the problems reflected in the first practical lesson, a new teaching scheme is redesigned on the basis of practical reflection. The new scheme aims at students' shortcomings in experiments, adjusts teaching strategies, and increases the discussion of students' experimental inquiry, including the design of experimental schemes, data collection, mutual discussion and questions about students' operability, especially the transfer of knowledge. It emphasizes the introduction and handling of mathematical relations in various design schemes, so that students can have in-depth discussions and questions.

Question 1: A small light bulb is marked with the words ",",the power supply voltage is 6V, the key and ammeter, and the sliding rheostat is marked with the words "50Ω, 1.5A". Now a voltmeter 15V is broken (0-3V is available). How to measure the power of small light bulbs through experiments?

[Teaching section 1]

Teacher: When the rated voltage of the small bulb is 3.8V, the voltmeter 15V is damaged. How to measure the power of small light bulbs?

Health: Connect a voltmeter in parallel at both ends of the sliding rheostat.

Teacher: The method is very good. Can you connect a voltmeter in parallel at the beginning with the sliding rheostat?

Health: Impossible.

Teacher: Why?

Health: After the circuit is connected correctly, when the key is closed, the sliding rheostat should be placed at the maximum. At this time, the voltage across the sliding rheostat exceeds 3V, so it cannot be directly connected in parallel.

Teacher: What should I do?

(After thinking and discussing)

Health: Can you first connect the voltmeter to the two ends of the small bulb and adjust the slider of the sliding rheostat so that the voltage at the two ends of the small bulb is 3V and the voltage at the two ends of the sliding rheostat is 3V? At this time, you can move the voltmeter, connect the voltmeter in parallel at both ends of the sliding rheostat, adjust the slider so that the voltage at both ends of the small bulb is 3.8V when the voltage is 2.2V, and observe that the ammeter reading is 0.3A, so that the power of the small bulb can be measured.

……

Question 2: A small light bulb with rated voltage of 6V, key, voltmeter and sliding rheostat are marked with "50Ω, 1.5A" but there is no ammeter in hand. How to measure the power?

[Lesson 2]

Teacher: Adjust the slider of the sliding rheostat so that the voltage at both ends of the small bulb is 3.8V At this time, the voltage at both ends of the sliding rheostat is 2.2V How do you know the resistance of the resistance wire in the connected circuit?

Health: Can you measure the length of the resistance wire?

Teacher: Why do you need to measure the length of the resistance wire to know the resistance value? * * * Page 3, current page 1 123 #p#

Health: Because the total resistance of the resistance wire of the sliding rheostat is 50 ohms and the total length is a constant value, the resistance value of the resistance wire in the access circuit can be obtained by measuring the length of the resistance wire in the access circuit by using the proportional method.

Teacher: What is your theoretical basis?

According to the law of resistance, when (material properties) and (cross-sectional area) are constant, R is proportional to L (length).

Teacher: Can you write this relationship?

Health: Yes.

Teacher: What tools are used for measurement?

Health: (after thinking) Use a scale.

……

After constant exploration and thinking, the students came up with a solution. By measuring the length of the resistance wire connected in the circuit, the resistance connected in the circuit can be obtained.

Question 3: A small light bulb has a rated current of 6V, a sliding rheostat marked "50Ω, 1.5A", two keys and an ammeter, but there is no voltmeter in hand. How to measure the power of small light bulbs through experiments?

[Teaching Segment 3]

Teacher: How to measure the current through the sliding rheostat with an ammeter?

Health: Can the circuit be partially short-circuited?

Teacher: How did the local short circuit happen?

Health: the two ends of the small light bulb are connected in parallel with the electric key. When the current indicator reaches 0.3A of the small bulb for the first time, close the parallel key to short-circuit the small bulb and measure the current in the circuit.

Teacher: Next, how do you get the voltage across the small bulb?

Health: divide the current when the circuit is partially short-circuited by the power supply voltage to obtain the resistance of the sliding rheostat connected in the circuit. Multiply the current by 0.3A to get the voltage across the sliding rheostat, and subtract the voltage across the sliding rheostat from the power supply voltage to get the voltage across the small bulb.

Teacher: Is there any other way to get the resistance of the sliding rheostat in the circuit?

Health: Can you measure it with a scale?

Teacher: Yes, you can try both methods.

……

Teaching reflection:

The second practice focuses on discussing and further improving students' comprehensive problem-solving ability, looking for theoretical basis in problem-solving methods, and making students understand that solving problems must have theoretical basis. The simplest tool (scale) can be used to solve difficult electrical problems. In practical teaching, it is found that students can collect data and calculate with mathematical expressions, but they will not organize in the form of tables. Tables are commonly used in experimental data processing, and teachers should let students learn such a science.

The third method: teachers guide in time, and students' inquiry consciousness is enhanced.

Teaching philosophy:

On the basis of the first two practices, the teachers in the group and I analyzed the lack of reflection in the second practice class. Everyone asked if we could set some more questions about the problems we had encountered, set some obstacles for students' cognition, expand the scope of positive thinking, let students design experimental schemes to solve practical problems without knowing the power supply voltage, and let students continuously enhance their awareness of inquiry and learn to find and ask questions initially. Then find a solution to the problem. On this basis, add a thinking question: a student has a small light bulb clearly marked "0.3A", a sliding rheostat marked "50Ω, 1.5A", and the voltmeter is broken. Knowing that the power supply voltage is about 6V, after thinking, a method for measuring the power of small light bulbs is worked out. There are many places to explore this problem in the experimental operation, which can be explored by students.

After discussion, the students finally got an ideal scheme. Connect the voltmeter to both ends of the small bulb, close the key and slide the rheostat to the maximum value. Record the readings of voltmeter and ammeter at this time, multiply the reading of ammeter by the maximum resistance of sliding rheostat to get the voltage at both ends of sliding rheostat, and add the voltages at both ends of small bulb to know the correct value of power supply voltage. Then, you can use the method to solve the problem (2). You can also measure the power of a small light bulb by solving problem (3). In the actual teaching practice, students can see the relationship between these data from the table given by the teacher or the question design table, and through recording and sorting out the data, they can draw appropriate conclusions from the table and learn the correct language expression.

Third, summarize and reflect:

The third practical class is an open class in the whole region. Students discuss electrical experiments through computer simulation analysis, observe phenomena, solve problems in experiments and think about unexpected problems in experimental methods. Through students' practical operation and teachers' demonstration, students' positive thinking is greatly stimulated and they actively participate in the teaching process. The teachers who attend the class have a deep influence on this teaching method of discussion experiment, which is worth learning.

Through three practices and two reflections, I realized that whether students can actively participate in classroom teaching, and whether the set inquiry questions (or question scenarios) and inquiry activities can be actively and effectively carried out, the following elements should be paid attention to in the teaching process:

1. The content of inquiry should be suitable for students' cognitive structure and ability foundation, and questions should have a sense of hierarchy and a certain cognitive slope.

2. Give full play to the integration of modern information technology and subject teaching, let students explore in multiple channels and directions, and enhance the depth of students' thinking.

3. In the students' inquiry activities, teachers should promptly answer questions and guide, and conduct interactive and cooperative inquiry.

Teachers must work hard in these aspects, make use of the phenomena in life, stimulate students' desire to explore actively, gradually explore the level of content through questioning, discussion and communication, set the slope of students' thinking, and explore ways to solve problems.

On this basis, give students more time to practice, students will find the limitations of various instruments in specific operations, and constantly reflect on them, so as to attract students to actively participate in the process of "exploring, trying, discovering and innovating". * * * Page 3, current page 2 123 #p#

Through the teaching and research activities of "three practices and two thoughts", I deeply realized the role played by professional researchers and the importance of teaching and research activities of all teachers in the teaching and research group, which brought new ideas and new teaching methods to my teaching. Classroom teaching is the main position of education and teaching reform. In teaching practice and reflection, only by constantly updating teachers' teaching concepts, constantly reflecting teachers' teaching behaviors, improving our teaching methods and perfecting our teaching strategies can we effectively improve physics teaching.