关键词: 咖啡因, 实验教学改革, 多维度探究, 教学价值, 科学思维

Abstract: To address the limitations of the classical “Caffeine Extraction from Tea leaves” experiment—including restricted material sources, methodological rigidity, limited investigative depth, and weak relevance to daily life—this study systematically optimizes the teaching approach through multi-source material selection, comparative methodology, and multidimensional analysis. The experiment employs three types of tea leaves with varying fermentation levels and two coffee powder samples from different geographical origins. Using a controlled variable approach, we designed two extraction methods (Soxhlet extraction and boiling water extraction) and established a dual quantitative analysis system incorporating both gas chromatography (GC) and high-performance liquid chromatography (HPLC) for precise quantification. While retaining the core Soxhlet extraction procedure, we designated purification techniques (sublimation and thin-layer chromatography) as optional extension modules for implementation when sufficient class time is available. Results indicate that although tea leaves contain higher absolute caffeine content, coffee beverages deliver greater caffeine intake per serving when typical consumption patterns are considered, thereby resolving the apparent contradiction between experimental data and common perception. The redesigned experiment has evolved from a basic operational exercise into a comprehensive inquiry platform that effectively engages students while simultaneously developing practical skills, scientific thinking, and innovative capacity.

Key words: Caffeine, Experiment teaching reform, Multi-dimensional inquiry, Teaching value, Scientific thinking