Fostering Pre-Service Vocational High School Teachers^ Conceptual Understanding of the Lambert-Beer^s Law in the Context of Electromagnetic Radiation-Solution Interaction Sarina Hanifah (a), Tiwi Nur Astuti (b), Elva Stiawan (c), Retno Ayu Puspita (d), Gusman Santika (e), Vida Zenitha Sudariasri (f)
(a*),(b),(d),(e),(f) Chemistry Education Study Program, Faculty of Mathematics and Natural Sciences, Universitas Negeri Jakarta, Indonesia
sarina.hanifah[at]unj.ac.id
(c) Military Chemistry Department, Faculty of Military Mathematics and Natural Sciences,
Republic of Indonesia Defense University, Indonesia
Abstract
Chemistry education in Vocational High Schools (SMK) requires prospective teachers to possess a strong conceptual understanding, particularly of concepts applicable to analytical chemistry. One key concept in this field is Lambert-Beer^s Law, which describes the relationship between electromagnetic radiation and the concentration of a substance in solution. This concept plays a vital role in spectrophotometric techniques, which are widely used for the quantitative analysis of various chemical compounds. To ensure that pre-service teachers do not merely memorize formulas procedurally but instead develop a deep conceptual understanding, effective learning strategies are needed to actively promote such comprehension. In this study, a PhET simulation of Lambert-Beer^s Law was implemented in conjunction with an inquiry-based learning model. Through this approach, students were expected to explore and investigate the relationship between wavelength and the color of absorbed or visible light, as well as manipulate cuvette length and solution concentration to observe their effects on absorbance and transmittance. These activities aimed to guide students in drawing conclusions about the meaning of Lambert-Beer^s Law as a representation of both physical and chemical interactions. The study adopted a quasi-experimental method with a one-group pretest-posttest design, involving 39 pre-service chemistry teachers enrolled in an Instrumental Analytical Chemistry course. The results indicated that PhET simulation supported by inquiry learning effectively fostered students^ conceptual understanding of Lambert-Beer^s Law as an interaction between electromagnetic radiation and chemical solutions. The N-gain value of 0.470 demonstrated the potential effectiveness of this approach in enhancing student learning outcomes. The results of the Wilcoxon Signed-Rank Test indicated a statistically significant difference between the pre-test and post-test scores (p < 0.001). These findings support the use of PhET simulation-based inquiry learning in helping teachers design lesson plans that facilitate student to master the Lambert-Beer^s Law.
