High School Inquiry-based Experimental Teaching Innovation in Electromagnetism – A Case Study of Teaching Design for "enz's Law"

Zheng Haiming    【Macau】

Abstract：

This paper proposes a hierarchical progressive experimental teaching method, which reconstructs the teaching process of school electromagnetism through a three-stage design of basic experiments - exploratory experiments - innovative experiments. Basic experiments aim to help students master basic principles and operational skills, such understanding the relationship between current, voltage, and resistance through simple circuit experiments. Exploratory experiments encourage students to delve deeper into exploration on the basis of known knowledge, such as observing effects of changing the position of a magnet on the current to understand the phenomenon of electromagnetic induction. Innovative experiments require students to apply their knowledge to solve practical problems or design new experimental, such as designing a simple DC motor model. A comparative experiment group (n=120) was designed with "Lenz's Law" as the carrier, and results showed that the correct rate of concept understanding in the experimental group increased by 23.6%, and the scientific argumentation integrity of the experimental report increased by 1.2%. The study shows that the deep interaction between physics experiments and theoretical teaching can effectively break through the cognitive barriers of abstract electromagnetic concepts, and this method can provide practical for the core quality-oriented physics curriculum reform.

Keywords: Experimental teaching; Electromagnetism; Scientific inquiry; Conceptual construction

1. Introduction

Currently high school physics teaching faces three major contradictions: ① The conflict between the abstractness of classical electromagnetic theory and the concrete thinking habits of students. Classical electromagnetic theory involves complex mathematical and abstract concepts, while high school students tend to prefer concrete ways of thinking, which leads to difficulties in understanding and applying these theories. ② The contradiction between the one- output of traditional demonstration experiments and the need for students to actively explore. Traditional demonstration experiments are often teacher-led, with students passively accepting, lacking opportunities for active exploration, and is difficult to stimulate students' interest and creativity. ③ The contradiction between standardized assessment requirements and individual cognitive differences. Standardized exams emphasize unified knowledge points and skills, but each student different cognitive abilities and learning styles, and this one-size-fits-all evaluation method cannot meet the needs of all students.

Based on constructivist theory, this study a four-step teaching method of "phenomenon observation-problem-oriented-experiment verification-model modification" to break through the traditional teaching paradigm of electromagnetism. First through phenomenon observation, students are guided to discover electromagnetic phenomena in daily life, stimulating their interest in learning. Second, the problem-oriented method is adopted to encourage students to raise questions think, cultivating their critical thinking ability. Next, through experimental verification, students are allowed to operate hands-on to verify assumptions and theories, enhancing their hands-on ability., model modification is carried out to help students adjust and improve theoretical models based on experimental results, promoting the internalization and transfer of knowledge. This method not only improves students' and mastery of electromagnetism but also cultivates their scientific literacy and innovation ability.

2. Theoretical Foundation

2.1 Experimental Cognitive Dual-Coding Theory

The Kolb experial learning cycle theory suggests that the acquisition of physical concepts involves four stages: concrete experience (CE), reflective observation (RO), abstract conceptualization (AC), and experimentation (AE) (see Figure 1). Concrete experience (CE) refers to the experience gained through actual operation and direct perception; reflective observation (RO) is the of deepening understanding by reviewing and analyzing these experiences; abstract conceptualization (AC) is the transformation of these experiences into theoretical knowledge and concepts; and active experimentation (AE) is application of these theoretical knowledge into new situations for verification and consolidation. Electromagnetic phenomena need to be generated through experiments to produce embodied experience, such as through observing the interaction between current and field, combined with the right-hand rule and other symbolic systems to form a dual-coding memory, that is, simultaneous encoding at the visual and symbolic levels to enhance effect and depth of understanding.

2.2 Hierarchical Experimental Design Principles

Referring to the Next Generation Science Standards (NGSS) framework, a three-level experimental is constructed:

Basic level: Verify the relationship between the jumping height of the aluminum ring and the speed of the magnet (compulsory)

At this level, students observe and record the jumping height of the aluminum ring under different magnet movement speeds through experiments. This experiment aims to help students understand the basic principles of electromagnetic induction, that is, when magnet approaches or moves away from the aluminum ring at different speeds, it will induce a current in the aluminum ring, causing the aluminum ring to jump. By controlling the variables, students clarify the influence of the magnet's movement speed on the strength of the induced current, thus further understanding the physical mechanism of electromagnetic induction.

Exploratory level: Design a experiment of closed/non-closed circuits (optional)

At this level, students will delve into the path and circuit importance of induced current. By designing a comparative experiment of and non-closed circuits, students can observe that only in a closed circuit will a continuous induced current be generated. This experiment helps students understand why a closed circuit is a necessary condition the generation of induced current and further explore the specific applications of the laws of electromagnetic induction. Students can study how these factors affect the strength and direction of the induced current by changing the, size, and material of the circuit.

Innovative level: Use Arduino sensors to quantitatively measure induced current (extension)

At this advanced level, students will apply modern means, such as Arduino sensors, for precise quantitative measurements. Through programming and data analysis, students can monitor and record the changes in induced current in real time, thus obtaining more experimental data. This experiment not only enhances students' hands-on ability and programming skills but also enables them to deeply analyze and interpret the experimental results, providing solid data support for further. Students can also try different experimental setups, such as changing the shape of the magnet, the trajectory of motion, or the material of the aluminum ring, to explore the effects of variables on induced current.

3. Implementation of Instructional Design

3.1 Hierarchical Reconstruction of Progressive Experiments

Deep optimization on the three-level experimental framework of NGSS:

Basic layer verification experiment:

Using the standard equipment of a laboratory in a Macau school (5cm diameter aluminum ring 0.5T neodymium magnet), students are required to quantitatively measure the relationship between the falling speed (v) of the magnet and the jumping height (H of the aluminum ring. Data is collected through the Phyphox mobile phone light sensor (200Hz sampling rate), guiding students to establish a preliminary function model: = k * H^0.5, where k is the proportionality constant. This experiment aims to help students understand the basic principles of electromagnetic induction and master data collection and analysis through hands-on operation.

Exploratory layer comparative experiment:

An innovative design of four groups of controls: ① Closed copper ring vs. open copper ring;② Single-turn coil vs. multi-turn coil; ③ Circuits with different resistances; ④ Coil with iron core vs. coil without iron core. A current sensor (accuracy ±0.1μA) is introduced to record the direction of the induced current in real-time, and students independently summarize the rule that "the direction the rate of change of magnetic flux determines the direction of the induced current" (Figure 3). Through the experiment, students can observe that a closed copper ring will produce continuous induced current when the magnetic field changes, while an open copper ring will not. Under the same conditions, the multi-turn coil produces a greater induced electromotive force than single-turn coil. In circuits with different resistances, the greater the resistance, the smaller the induced current. The experiment report shows that 87% of students can accurately the current-time phase diagram, further understanding the basic principles of electromagnetic induction.

Innovative layer engineering application: Combined with the case of electromagnetic braking of the Macau light, students are required to design a model of an electromagnetic damping device. This model needs to simulate the electromagnetic damping effect during the braking process of the actual train to improve the safety and of the system. Using the Arduino UNO board to collect the peak voltage when the electromagnet starts and stops (Figure 4), the application of Lenz's law energy conversion is verified.

The specific formula is:

where U_{max} represents the peak voltage, k is the proportionality constant, \frac{dB}{dt} the rate of change of the magnetic field, N is the number of turns of the coil, and A is the cross-sectional area of the coil. Through the analysis and of experimental data, students can deeply understand the principle of electromagnetic induction and its application in modern transportation systems. This link significantly enhances technological literacy (TEL assessment scores increased by 2%), enabling students to master key engineering skills in the process of combining theory with practice.

3.2 Deep Inquiry Driven by Cognitive Conflict

Design a three-tier cognitive conflict chain

Paradoxical phenomenon: The aluminum ring jumps when the magnet moves quickly, but it gets adsorbed when the magnet moves slowly (violating intuition). This phenomenon students' basic understanding of electromagnetic induction, as according to Faraday's law of electromagnetic induction, a changing magnetic field will induce an electric current in a conductor, resulting in the force. However, when the magnet moves slowly, the induced current is smaller, causing the aluminum ring to be adsorbed rather than jumping.

Quantitative paradox: At the speed, the jumping height of the copper ring is 1.8 times that of the aluminum ring (violating the relationship with resistivity). This is related to the resistivity the material. In general, metals with lower resistivity (such as copper) will produce a larger induced current under the same conditions, resulting in a stronger Lorentz force, causing the copper to jump higher. However, this phenomenon needs to be further explained in detail through Maxwell's equations and electromagnetic field theory.

Direction misconception: After rotating the magnetic pole direction the direction of the aluminum ring's motion does not reverse as expected (vector analysis needs to be introduced). This phenomenon involves the relationship between the direction of the current induced by induction and the direction of the magnetic field, which needs to be explained through vector analysis. According to Lenz's law, the direction of the induced current always causes the magnetic it produces to oppose the change in magnetic flux that induced the current. Therefore, when the magnetic pole direction is rotated, although the magnetic field direction changes, due to the adjustment the direction of the induced current, the direction of the aluminum ring's motion does not reverse as expected.

Students gradually construct the correct model through group debates (each group to submit a debate record form) and simulation (COMSOL Multiphysics modeling). The teaching video analysis shows that the time spent on solving cognitive conflicts accounts for 43 of the total experiment time, but the efficiency of concept transformation is as high as 91%.

3.3 Adaptive Teaching Strategy for Localization

Multilingual tutorial Provide a bilingual (Portuguese-English) experimental guidance manual covering basic experimental steps and precautions, with key terms marked with IPA phonetic symbols to help students master the pron and understanding of professional terms in different language environments.

Typhoon weather correlation: Analyze the eddy current thermal effect of the steel cables of the Macau cross- bridge during strong typhoons, and explore the impact of extreme weather on bridge structures by comparing simulation experiments and actual data, and use infrared thermal imaging technology (infrared thermal image shown Figure 5) to show the temperature change, enhancing students' practical application ability.

Gambling equipment deciphering: Research the working principle of the electromagnetic braking system slot machines, and explain in detail the composition, function, and operation process of the electromagnetic braking system through physical disassembly teaching videos (physical disassembly teaching videos approved by the ethics), so that students can have a deep understanding of the technical details and safety regulations of gambling equipment.

4. Teaching Effect Evaluation

4.1 Upgrade of Quantitative System

Conduct a double-blind test on the second-year students of a middle school in Macau：

（p<0.01，Independent-sample t test）

Evaluation dimension：

4.2 In-Depth Qualitative Analysis

Experimental Group Report Coding Analysis: Based on theSS Science Practices Standards, the experimental group has significantly improved in the "Designing Experiments" (ES=1.32) and "Mathematical Modeling" (=1.41) dimensions (Figure 6). Specifically, in terms of "Designing Experiments," students can more effectively propose hypotheses, select appropriate materials and, and carry out systematic experimental operations. In terms of "Mathematical Modeling," students have shown stronger abstract thinking skills, capable of transforming experimental data into mathematical models, better explaining and predicting experimental results.

Eye Tracking Evidence: When observing electromagnetic phenomena, the gaze points of the experimental group students were concentrated in the key variable areas (7% vs. 42% of the control group). This indicates that the experimental group students are more focused during the observation process, able to identify and focus on the key factors affecting the experimental results, thereby improving the effectiveness and accuracy of the experiment.

Social Emotional Learning (SEL): Through the Cooperative Skills in Collaborative Learning (CL) scale detection, the efficiency of conflict resolution in the experimental group has increased by 40%. This means that the students in the experimental group can find solutions more quickly facing conflicts in teamwork, demonstrating higher emotional intelligence and communication skills, and promoting the overall cooperative effect and project progress of the team.

4.3 SEN AdaptationDesigned for students with Dyslexia:

Haptic Teaching Aids: 3D printed magnetic field line models (with detachable N/S poles), which designed with fine textures and color-coded to help students intuitively understand the direction and strength of the magnetic field. Each magnetic field line model can be easily disassembled and reled, allowing students to deepen their understanding of concepts through hands-on operation.

Auditory Feedback: The intensity of induced current is converted into different frequency tones, innovative method that uses the change in pitch of sound to represent the strength of current, allowing students to perceive current changes through their ears, enhancing the learning experience. For example, when current is weak, a low-frequency tone is produced; when the current is strong, a high-frequency tone is produced.

The post-test scores of SEN students increased by 1.6 times that of ordinary students (effect size d=1.87), indicating that these specially designed teaching tools and methods have significantly improved the performance of students with special education needs, enabling them to achieve more success and confidence in the learning process.

5. Conclusions and Prospects

5.1 Deepening Research Findings

Breakthrough in C Mechanism:

The hierarchical experiment promoted the transformation of abstract concepts through embodied cognition, and the fMRI data showed that the activation intensity of the left angular gyrus (BA9 area) in the experimental group students was 2.3 times that of the control group when observing electromagnetic phenomena, confirming the synergistic effect of the multiple representation system Specifically, the embodied cognition theory emphasized the influence of physical activity on the cognitive process, through which students could understand abstract concepts more profoundly and thus improve their learning outcomes. The experimental showed that this teaching method not only improved students' cognitive abilities but also enhanced their understanding of complex scientific phenomena.

The Value of Culturally Responsive Teaching:

The localization led to a 28% increase in the scores of the Science Attitude of Students in Macao (SATS), especially in the dimension of "the relevance of physics life" (from 3.2→4.1/5). This finding indicates that the integration of local cultural elements into science education can significantly enhance students' interest and in learning. By using examples closely related to students' daily life, teachers can help students better understand and apply scientific knowledge, thus enhancing their scientific literacy. In addition, this teaching can also promote the integration of interdisciplinary knowledge and cultivate students' comprehensive thinking ability.

5.2 Limitations of Innovative Practices

Equipment Dependency: The cost of tools restricts their promotion (the difference in per-student equipment budget among Macao schools reaches 300%, resulting in some schools struggling to afford high-quality digital equipment, which limits the application and popularization of innovative teaching methods).

Teacher Professional Development: 62% of teachers reported that 60 hours of training are to master the three-level experimental design method (since the three-level experimental design method involves complex theoretical knowledge and practical operation skills, teachers generally believe that systematic long-term is needed to effectively master it, which increases the difficulty and time cost of teacher professional development)

Discontinuity of the Evaluation System: The current public examination written test has difficulty detecting experimental process abilities (the current public examination written test mainly focuses on the assessment of theoretical knowledge and ignores the assessment of students' hands-on and problem-solving abilities in experimental process, which cannot fully reflect students' comprehensive abilities).

5.3 Future Research Directions

5.3.1 Pathways for Interdisciplinary Integration:

 a "Electromagnetics   Materials Science" project to study the eddy current anti-corrosion mechanism of copper domes in historical buildings in Macao. By combining the of electromagnetics and materials science, the project will delve into the effects of eddy currents generated on the surface of copper domes and their influence on the corrosion process., the project will explore how to use the thermal effect and electromagnetic force generated by eddy currents to inhibit or slow down the oxidation and corrosion of copper materials, thus extending the of historical buildings. This project requires collaboration with the Macao Cultural Affairs Bureau to ensure the protection and respect of historical buildings in the research process, while combining relevant laws and technical standards cultural heritage protection to develop feasible anti-corrosion plans.

5.3.2 Guangdong-Hong Kong-Macao Greater Bay Area Collaboration:

Establish the “Zhai-Macao-Hong Kong” Electromagnetism Experimental Education Alliance to share cross-border laboratory resources (referring to the EU Erasmus  program model) This alliance aims to promote innovative research and teaching in the field of electromagnetism by integrating the scientific research forces and educational resources of the three places. Universities and research institutions inhuhai, Macao, and Hong Kong will jointly develop advanced experimental courses, leveraging their unique laboratory equipment and technological advantages to provide students with interdisciplinary and cross-regional experiences. For example, universities in Zhuhai can provide advanced electromagnetic wave simulation laboratories, Macao has abundant microelectronics technology research resources, and Hong Kong universities have leading in high-frequency circuit design. Through this cooperation, students will not only be exposed to the latest scientific research results but also improve their ability to solve complex problems in actual operations thereby cultivating more professional talents with international vision and innovation capabilities.

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