Teaching Innovation Driven by Comparative Experiments in Real Life: A Case Study of Electrote Solutions in High School Classrooms in Korea

Kim Sang-Seong 【Korea】

Abstract

This paper uses the teaching of “the conductivity of electroly solutions” as an example, and designs a three-level classroom model of “life situation-comparative experiment-interdisciplinary project”. By using local cases (such as conductivity test of kimchi brine) to stimulate the motivation of inquiry, the method of controlling variables and parallel experiments are introduced to strengthen scientific thinking, and family experiment tasks are to deepen the ability of application. The practice shows that the model significantly improves students' experimental design ability (the classroom participation rate has increased by 37%) and the awareness cross-disciplinary integration, and provides a new path for the teaching innovation of chemistry in Korea.

Keywords: Comparative experiments; Life-oriented teaching; Electroly solutions; Scientific inquiry; Control variable method

1. Introduction

The revised education curriculum in Korea in 2022 emphasizes that "scientific literacy should be rooted in practice" (Ministry of Education of Korea, 2022). However, there are still two major pain points in the current high school chemistry classroom: one is procedural experiment design, such as in the teaching of electrolyte, which is limited to the single experiment of NaCl solution conductivity test and acetic acid solution pH value determination in textbook, students only play the role of passive executors to verify the established theoretical conclusions, lacking the opportunity for autonomous inquiry and problem solving; the other is the obvious disciplinary barriers, content of chemistry teaching and the knowledge of electricity in physics (such as circuit connection, the concept of current intensity), the conductivity of body fluids in biology (such as the electroly composition of human blood and tissue fluid and its physiological significance) and other fields have not been effectively related, resulting in students having difficulty in forming a cross-disciplinary knowledge network and comprehensive ability.

In order to break through this limitation, this study draws on the results of comparative research on Chinese and Korean teaching models: Korean education focuses on the cultivation of " subjectivity" and "practical ability", encouraging students to actively construct knowledge through inquiry activities; Chinese classrooms, on the other hand, have significant advantages in the systematicness and of disciplinary knowledge, which can lay a solid disciplinary foundation for students. Integrating the strengths of both sides, this study constructs an innovative teaching framework of “life situation introduction → comparative exploration → cross-disciplinary project production”, and carries out practice in two parallel classes in the second year of Zincan High School

2. Theoretical Basis and Case Design

2.1  Extraction of Innovation Points

Local life situation drive: Instead of traditional inorganic solution experiments, the “conductivity kimchi brine”, which is familiar to Korean students, is used to replace it, which is related to family diet culture; kimchi, as a traditional Koreanmented food, uses brine in the production process, which is rich in electrolytes such as sodium chloride, and is commonly seen in daily life. Students can directly feel the of electrolyte solutions by hand-pickling kimchi or observing the brine in the kimchi jar at home, which closely connects the abstract physical and chemical knowledge the familiar diet culture and stimulates interest in learning.

Multiple comparison experimental design: Set up a blank group (distilled water), a control variable (concentration/temperature), and a parallel experiment group (3 repetitions) to cultivate rigorous thinking; specifically, the blank group uses pure distilled water as a control, its phenomenon of non-conductivity; the control variable group changes the concentration of brine (such as low concentration, medium concentration, high concentration) and temperature (such as room, heated, cooled) respectively, records the changes in conductivity under different conditions, and clarifies the influence of concentration and temperature on the conductivity of electrolyte solution; The parallel experiment ensures the reliability of the data and the reproducibility of the experimental results through three independent repeated experiments, guiding students to experience the rigor of scientific inquiry in operation, learning control variables, analyze errors, and draw conclusions;

Low-cost interdisciplinary task: Make a "Human Body Conductivity Safety Alert Device", which integrates knowledge of physical circuits biological electrolytes. This task uses the circuit knowledge that students have mastered (such as series circuits, switches, indicator lights) and the principle of electrolyte conductivity to design a simple: when the hands of the human body touch the two electrodes of the alert device, because the human tissue contains a large amount of electrolyte (such as sodium ions, potassium ions etc.), a closed loop is formed to make the circuit conductive, the indicator light lights up, and a safety warning signal is issued. This process not only allows students practice building physical circuits but also to understand the role of electrolytes in the human body, to achieve the organic integration of physics and biology, and at the same time, the material is low (such as using waste batteries, small light bulbs, wires, electrode sheets, etc.), which is easy to promote and implement in the classroom.

2. 2  Detailed description of teaching cases

2.2.1 Class 1: Introduction of life problems (15 minutes)

【Situation】Play a video of the process of homemade kimchi at home, which clearly shows that a large amount of salt needs to be added to the kimchi during pickling and stirred evenly, and then kimchi is placed in a sealed container, and the liquid in the container gradually increases. After the video playback is complete, the teacher guides the students to think and ask:Students, in our daily life, we may hear some elders say 'kimchi brine is highly conductive, and if it comes into contact with electricity, it may cause shock', for example, what grandma often says '짠 김치 국물은 감전 위험이 있다' (Salty kimchi soup at risk of electric shock), is this statement scientifically based? Please try to analyze whether there is really a risk of electric shock in kimchi brine based on the knowledge electricity we have learned before."

【Tools】The teacher distributes a "Learning Task Sheet" (학습안내문) to each student, which contains a detailed design flowchart, divided into seven steps: "Raise a question—Make a hypothesis—Design an experiment—Conduct the experiment—Collect data—Draw a conclusion—Exchange reflect", each step is equipped with specific operation instructions and precautions. In addition, the task sheet also specially marks the safety regulations of this inquiry activity, including: the need use low-voltage power supply (below 3V) during the experiment, wear insulating gloves to operate, prohibit inserting wires directly into kimchi brine, clean the experimental in time after the experiment, etc., to ensure the personal safety of students during the inquiry and the smooth progress of the experiment.

.2.2 Class 2:parative experiment exploration (40 minutes)

The experimental design is shown in the table.：

[Key Operations]

Guide students to design the "concentration-conductivity" coordinate independently (training in the method of controlling variables); in the process of guiding students to design the "concentration-conductivity" coordinate graph independently, it is necessary to clearly require to use the solution concentration as the abscissa and the conductivity as the ordinate, and through plotting the conductivity data points corresponding to different concentrations of solutions, to analyze the quantitative between the two. In this process, the teacher should emphasize the core idea of the method of controlling variables, that is, to keep other influencing factors such as temperature and the of solution unchanged, and only to change the concentration of the solution, so as to accurately investigate the influence law of the concentration on the conductivity. At the same time, students can guided to consider the details such as the unit annotation of the coordinate axis, the precise dotting of the data points, and the smooth connection of the curve, so as to cultivate rigorous scientific experimental design ability.

Emphasize the necessity of parallel experiments: "Taking the average of three measurements can reduce accidental errors" (cultivating scientific attitudes); the experimental operation link, it is necessary to emphasize the importance of parallel experiments to students. By making three independent measurements of the same concentration of solution and taking the arithmetic mean of the conductivity data, it can effectively reduce the error caused by accidental factors such as instrument accuracy, reading deviation, and environmental fluctuations, and improve the accuracy and reliability of the experimental results The teacher can explain by giving examples, such as a certain measurement due to slightly faster operation resulting in a higher reading, another due to slightly slower operation resulting in a lower reading, the third measurement is relatively accurate, and the average of the three cancels out some accidental errors, making the results closer to the true value. This process not only enables students to scientific methods of experimental data processing but also cultivates their realistic, rigorous, and meticulous scientific attitudes and the spirit of pursuing precision in experiments.

2.2.3 Classment 3: Cross-Disciplinary Project Production (Homework)

It is required that the group use LEDs, resistors, and batteries to design a simple circuit to test

The effect of human sweat (before and after exercise) on the brightness of the circuit → explain the principle of "wet environments are prone to electric shock";

Submit report questioning the biological electrolysis (cite physiology resources)

The specific task requirements are as follows: each group needs to complete a cross-disciplinary project production after class, core of which is to use basic electronic components to construct a simple circuit. The required materials include LEDs (it is recommended to use 3V low-voltage LEDs to ensure safety, resistors of appropriate resistance (to be selected according to the rated current of the LED, such as 200Ω-1kΩ), dry batteries (15V or 3V, the quantity to be determined according to the circuit design), and connecting tools such as wires and switches. The circuit design needs to ensure that the can emit light normally, and the switch can control the on-off.

The test content is to explore the difference in the conductivity of human sweat before and after exercise and its on the brightness of the circuit. The specific operation steps include: first, before exercise, let the group members lightly touch the part of the circuit that comes into contact with the skinyou can design a simple electrode device, such as copper or aluminum sheets as conductors), and observe and record the brightness of the LED; then engage in moderate exercise (such jogging, jumping rope, etc., lasting for 5-10 minutes), and immediately repeat the above operation after exercise, and again record the changes in the brightness the LED. Through comparing the difference in the brightness of the LED in the two experiments before and after exercise (which can be qualitatively described as "significantly brighter," "s brighter," or "no significant change"), analyze the electrolyte components (such as sodium ions, potassium ions, etc.) in the sweat on the impact of the conductivity.

Based on the experimental results, it is necessary to explain the principle of "easy electrocution in humid environment". When the body is in a humid environment, the amount of sweat on the skin surface increases, and sweat contains a large number of ions that can move freely, which significantly reduces the body' resistance. According to Ohm's law I=U/R, when the voltage U is certain, a decrease in resistance R will cause an increase in the current I passing the human body. When the current exceeds the safe threshold (generally considered to be over 10mA that may cause harm to the human body), it is easy to an electric shock accident. Therefore, a humid environment will increase the risk of electric shock, which is also why it is necessary to avoid contact with electrical equipment in rainy days or when hands are wet.

In addition, the group also needs to submit a "Biological Electrolysis Questioning Report", which needs to cite relevant physiological information and conduct in-depth analysis of the experimental phenomena. For example, you can consult the information to understand the composition of human sweat (mainly containing electrolytes such as sodium chloride potassium chloride), and explain how these electrolytes enhance the conductivity of the solution. In combination with physiological knowledge, it is necessary to explain the mechanism of accelerated human metabolism and sweat secretion during exercise, which leads to enhanced skin conductivity. At the same time, it is possible to question or supplement the general knowledge of "humid environment is prone to shock", such as discussing the difference in electrolyte concentration of sweat among different individuals, and the specific impact of environmental humidity on skin resistance. By supporting the report with literature or reasoning, the scientificity and persuasiveness of the report are enhanced. The report should include the experimental design idea, data recording and analysis, explanation of the principle and questioning, etc., with a minimum of 800 words.

3. Implementation Effect Analysis

A comparison between Class 3, Grade 2, Zhenchuan High (the experimental group) and the parallel class (the control group)：

Typical Progress Case:

Students discovered that "the conductivity of pickle brine increases with time," and extended their exploration to investigate the ionization phenomenon of lactic acid bacteria metabolites.

4. Discussion and Suggestions

4.1 Summary of Innovation

aking the limits of textbooks: Reconstructing experimental content with local food culture, such as introducing the traditional pickling fermentation process into biochemistry experiments, and measuring the changes in the of lactic acid bacteria, pH value, and nitrite content at different fermentation stages to help students understand the role of enzymes, microbial metabolism, and food preservation principles in a cultural context, echoing the core concept of "combining scientific knowledge with daily life" emphasized in the "Life Science Education" policy of Korea;

Advanced experimental thinking: From blank control experiments (such as verifying the effect of vitamin C on the oxidation of iron ions) to complex control variable experiments (such as exploring the separate and interactive effects of temperature pH on the activity of amylase), and then to the design of parallel experiments (such as setting up 3 groups of repeated experiments to determine the average value and deviation of the reaction rate under the same conditions), forming a scientific inquiry logic chain of "observing phenomena → proposing hypotheses → designing experiments → controlling variables → collecting data → analyzing → drawing conclusions", effectively cultivating students' critical thinking and experimental design ability;

Innovation in assessment methods: The experimental report adds a "reflective self-evaluation link, requiring students not only to record the experimental steps and results, but also to deeply analyze the possible sources of errors that may occur during the experiment, such as instrument precision limitations lack of operational standardization, and interference from environmental factors (such as the impact of temperature fluctuations on reaction rate), and to propose improvement suggestions, such as "if a precise electronic balance is used, it can reduce weighing errors", "preheat the constant temperature water bath to ensure that the reaction temperature is constant", thus promoting students' indepth thinking and self-improvement of the experimental process.

4.2 Implementation Suggestions

Resource optimization: Using micro-experiments (such as using a dotting plate replace traditional test tubes for observing chemical reactions and exploring the properties of substances) significantly reduces the use of experimental consumables, thereby effectively reducing the cost of the experiment. This not only the core requirements of "reduction" and "resource efficient use" in the concept of green chemistry, but also cultivates students' awareness of environmental protection and conservation under the premise ensuring the effect of experimental teaching.

Teacher collaboration: Jointly develop interdisciplinary joint teaching plans for "electrolyte conductivity-resistance calculation" with physics teachers and integrate the determination experiment of solution conductivity in chemistry with the related knowledge of Ohm's law and resistance calculation in physics, to design a series of exploratory activities, as letting students determine the conductivity of different concentrations of sodium chloride solution, and combine the physical formula R=U/I for data analysis and calculation, to strengthen the internal connection disciplines, and help students build an interdisciplinary knowledge network, and improve comprehensive application ability.

5. Conclusion

This case integrates comparative experiments and interdisciplinary applications into electrolyte through the life-oriented carrier of "pickle brine conductivity", making abstract concepts concrete. Practice has proved that this model effectively enhances the scientific inquiry ability and innovative thinking Korean students, and provides a replicable model for the reform of chemistry classrooms. It will be expanded to topics such as "pH regulation of food additives" to deepen the between life and science.

References

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[2]Ministry of Education. (022). 2022 Revised Science Curriculum. Seoul: Ministry of Education.

[3]Park, J. (2024) Guidance for Designing Real-Life Connected Chemistry Experiments. Journal of the Korean Chemical Education, 18(3), 45-59.

[4]Lee, M. (2025). A Plan for Cultivating Scientific Thinking Ability through Controlled Experiments. Journal of Science Education, 0(1), 77-91. 6

[5]OECD. (2024). PISA 2025 Science Framework Paris: OECD Publishing.