Teaching Practice of Life-oriented Inquiry in Middle School Chemistry -- Taking the "Properties of Acids,ases, and Salts" Classroom Teaching as an Example

Li Mingyao 【Singapore】

Abstract:

This paper takes the "Properties of Acids, B, and Salts" unit in Singapore middle school chemistry as a case study and innovatively designs a "Chemical Secrets in Homemade Soda" life-oriented inquiry project Through problem-based learning (PBL), hierarchical task cards, and dynamic assessment rubrics, the integration of teaching, learning, and assessment is achieved.1 The practice shows this model significantly enhances students' macro-identification and micro-analysis abilities. The experimental group has a 23.5% higher accuracy rate in the O-Level chemistry on the topic of acids, bases, and salts than traditional teaching, and it also effectively promotes interdisciplinary thinking development.

Keywords: Life-oriented inquiry; Integration of teaching learning, and assessment; Hierarchical tasks; Dynamic evaluation; Singapore middle school chemistry

1. Introduction

The Singapore Ministry of Education's "Secondary Science Syllabus revised in 2023 clearly states the requirement to "understand scientific knowledge in real-life contexts." Acids, bases, and salts, as core concepts in school chemistry, often lead to a cognitive gap in students due to their abstract nature in traditional teaching. This study is based on constructivist theory and refers to the "Kitchen Chemistry module in the local textbook "Chemistry Matters" to develop an inquiry course with homemade soda as the main line. The aim is to verify the promoting effect of life-oriented on concept internalization.

2. Framework of Innovative Teaching Design

2.1 Overall Structure (Three-stage Progressive Model)

A[Situation Introduction: Analysis Soda Recipe] --> B[Experimental Inquiry: Property Verification] When analyzing the soda recipe, it is necessary to understand the main ingredients of soda, includingic acid, sugar, acidity regulators, and flavorings, etc. Through experimental inquiry, the content of these ingredients and their interactions can be verified. For example, theic acid content can be determined by titration, and the types and concentrations of sugar and flavorings can be analyzed by high-performance liquid chromatography (HPLC) In addition, the effectiveness of the acidity regulator can be verified by pH value testing.

B --> C[Transfer Application: Design of Water Quality Testing Scheme] on the property verification of each ingredient in the soda recipe, the relevant technology can be applied to the design of water quality testing schemes. For example, by using titration and HC technology, the carbonate hardness, organic matter, and microbial pollution of drinking water can be detected. At the same time, by pH value testing, the acid-base state of water quality can be assessed to ensure the safety and suitability of drinking water. In addition, other detection methods such as conductivity measurement and heavy metal detection can be combined toively assess the water quality and formulate a scientific and reasonable water quality testing scheme.

2.2 Core innovations

Living up the experimental equipment

To make the experimental process more closely resemble daily life, we have undergone a-up transformation of traditional experimental equipment. Firstly, we replaced the traditional analytical balance with an electronic kitchen scale, which is not only easy to operate but also has an accuracy of up 0.01 grams, fully meeting the high precision requirements of the experiment. Secondly, we utilized pH test paper color cards to develop a mobile scanning program, which allows for rapid acquisition of pH values by scanning the paper color through the mobile phone camera, effectively avoiding the complexity and cost issues associated with using virtual reality (VR) devices. In addition we innovatively designed a new type of experimental instrument named "Multiple-hole Dropper Bottle" (patent number SG2025-CHEM001), features multiple independent dropper holes, enabling the precise addition of various reagents simultaneously, greatly improving the efficiency and accuracy of the experiment. These innovations not only simplify the experimental process reduce the cost of the experiment but also make the experimental operation safer and more convenient, bringing new possibilities to the fields of education and research.

Hierarchical task card

3. Classroom teaching records analysis

3.1 Pre-class Diagnosis (5 minutes): Before start of each class, the teacher will conduct a 5-minute pre-class diagnosis to understand the students' mastery of the content to be learned. This not only helps the adjust the teaching plan to ensure the pertinence and effectiveness of the teaching content but also helps students preview in advance and clarify learning objectives. Through simple questioning, mini-tests, discussions, the teacher can quickly identify students' knowledge blind spots and provide necessary guidance and support in time, thereby improving classroom efficiency and students' learning outcomes.

Typical errors:Lemon is acidic, so it contains hydrochloric acid." "Confused organic acids with inorganic acids."

In fact, the main acidic component inmons is citric acid, which is an organic acid, not inorganic acids such as hydrochloric acid. Citric acid not only gives lemons their distinctive sour taste but has a variety of health benefits, such as promoting digestion and antioxidant effects. Hydrochloric acid, on the other hand, is a strong corrosive inorganic acid that is used in industry and laboratories and is harmful to humans. Therefore, it is incorrect to mistake the acidity of lemons as containing hydrochloric acid, which reflects a miscon about the classification and properties of acidic substances. It is essential to distinguish correctly between organic and inorganic acids for the popularization and application of scientific knowledge.

3.2quiry stage (30 minutes)

Situational task: Make low-sugar soda for the school carnival

During this inquiry stage, students will delve into how to low-sugar soda to meet the needs of healthy eating. First, students need to understand the ingredients and production process of traditional soda, including the source of high sugar content and potential impact on health. Next, they will explore the choice of alternative sweeteners, such as natural sweeteners (e.g., stevia, erythrit) or artificial sweeteners (e.g., aspartame, acesulfame potassium). Through experiments, students can compare the taste, solubility, and of different sweeteners.

In addition, students also need to consider other factors, such as the color, taste, and carbonation of the soda. They can adjust the color adding natural dyes (such as carrot juice, purple cabbage juice) and use a carbonator to control the amount of carbonation. To ensure the safety and palatability the final product, students should conduct multiple trials and invite classmates or teachers to taste and provide feedback.

Finally, students will summarize their findings and prepare a detailed report outlining their sweetener, production method, and test results. This report will be presented at the school carnival, explaining the benefits and production process of low-sugar soda to the audience

Group experiment records (typical cases)：

Concept Generation Key Conversation:

Teacher: "What is the composition of the bubbles? How can it be proven?"

Student A:CO₂! It can be proven by the clarification of limewater turning turbid. When carbon dioxide gas is passed through clarified limewater, it forms calcium carbonate precipitate, the solution turbid, thus proving that carbon dioxide exists in the bubbles." (Macro → Symbol Transformation)

Student B: "HCO₃⁻ H⁺H₂CO₃→CO₂↑. This reaction process shows that bicarbonate ions combine with hydrogen ions to form carbonic acid, which then decomposes into carbon gas and water, explaining the formation mechanism of the bubbles." (Microscopic Analysis)

3.3 Evaluation Link (10 minutes)

Investigation Process Evaluationric

4. Verification of Teaching Effectiveness

4.1 Quantitative Data Analysis

Through quantitative data analysis of the 2024 academic year 8 Class 3 of Nanyang Girls' High School (the experimental group) and the parallel class (the control group), we can gain a deeper understanding of the of different teaching methods on students' learning outcomes. Specifically, the experimental group adopted a brand-new interactive teaching method, while the control group continued to use the traditional lecture-based model. Through the comparison, we found that the average score of the students in the experimental group was significantly higher than that of the control group. In addition, students in the group showed higher enthusiasm in the classroom, frequently raising their hands to speak, actively participating in group discussions, and demonstrating stronger understanding and creativity in their homework after class.

4.2 Qualitative Feedback

Student Reflections Excerpt:

"By adjusting the sweetness andness of the soda, I finally understood that buffer solutions are not magic! This experiment made me realize the practical application of chemistry in daily life, beyond just textbook theories. For example we can control the taste of a drink by adjusting the composition of the buffer solution, which is not only fun but also very practical." - Student Chen (Science Journal)

Evaluation:

"My child took the initiative to clean the bathroom scale with vinegar, which is a real-life transfer that happened in the classroom. He told me that the ac acid in the vinegar can react with the calcium carbonate in the scale, thus removing it. The application of this knowledge made him feel proud and more proactive in participating in household, which is truly a success case of education." - Parent Feedback Form

5. Reflection and Direction for Improvement

5.1 Innovative Practical Value

Address Localized Teaching Pain Points:

Integrating the O-Level examination point "salt preparation" into the soda crystallization experiment allows students to understand the chemical reaction process moreuitively through hands-on operations. For example, students can be guided to observe the speed and shape of different types of salt crystallizing in soda water during the experiment, thus deep their understanding of the concepts of solubility and saturated solutions.

Using Singapore's tap water samples for hardness testing (linked to PUB's water quality standards) not helps students understand the characteristics of local water resources but also cultivates their awareness of environmental issues. By comparing the hardness data of tap water from different areas, students can explore the impact water quality on daily life and come up with specific suggestions to improve water quality. In addition, this experiment can also be combined with mathematical statistical methods to enhance students' data analysis.

Cultivating Sustainable Development Literacy:

It requires us to start from every detail in our daily lives. Taking the example of commercially available soda, its sugar content is as high as about 4 teaspoons per 100 milliliters, which is harmful to health if consumed over a long period and also increases the burden on the environment In comparison, homemade soda allows for the control of sugar intake and significantly reduces the carbon footprint. By making our own soda, we can avoid using the aluminum cans used for commercially available, thus reducing the energy consumption and environmental pollution associated with the mining and processing of aluminum resources. In addition, homemade soda can also choose to use natural ingredients, such as fruits,, etc., to further improve the health value and environmental benefits of the beverage. Therefore, to cultivate sustainable development literacy, we must not only focus on personal health but also consider impact on the environment, take practical actions to reduce waste and pollution, and promote the popularization of green lifestyles.

5.2 Issues to be Optimized

Challenges Differentiated Teaching: 30% of students took longer than expected to complete the challenge layer tasks, indicating that some students face significant time pressure and learning obstacles when facing highdifficulty tasks. This phenomenon may be related to individual differences, learning habits, and the degree of understanding of specific content among students

Improved Scheme:

a. Establish an “Elastic Time Bank” (where fast groups can accumulate operational time) by students who perform exceptionally well to earn extra time after completing tasks, which can be utilized to tackle more complex challenges when needed. This not only incentivizes high-achieving students also provides flexible space for students who need more time to grow.

b. Develop a mobile experimental kit (for pre-experiment at home) that enables students to prepare for experiments advance at home, familiarizing themselves with the steps and required materials. This can not only reduce the time spent on experiments in the classroom but also help students grasp the basics before class enhancing classroom efficiency. Additionally, the mobile experimental kit should be designed to cater to the needs of different students, offering a variety of difficulty levels and interaction methods to accommodate different learning styles ability levels.

References:

【1】Singapore Examinations Board. O-Level Chemistry Specimen Papers 2025.

【2】MOE Cambridge CEQ Examination Guide. Singapore Press, 2024.

【3】Tan K.W.《Chemistry Matters》2nd Ed. Cavendish, 2023: 78-82.

【4】Guangdong Provincial Department of Education. Case Studies of Innovative Design in Middle School Chemistry. Higher Education Press, 2005.

【5】Wang Lei. Error Analysis and Teaching Transformation of Experimental Methods in Life- Experiments [J]. Chemical Education, 2023(5): 61-65. (Experimental Methodology)

【6】UNESCO.uational Learning Assessment Framework in STEM Education [R]. Paris: 2022. (International Assessment Standards)

【7】NGSS. Penetration Path ofdisciplinary Concepts in Chemistry Teaching [EB]. 2023.