Adapting Meaningful Learning Strategies for an Introductory Laboratory Course: Using Thin-Layer Chromatography to Monitor Reaction Progress

Abstract

Introductory-level laboratory courses provide students with hands-on experience using the discipline's tools and theories. These courses often rely on recipebased experiments due to the constraints of large enrollments, short lab periods, and the desire to minimize complexity. In addition, covering a breadth of topics can lead to a fragmented curriculum with little carryover in learning from week to week. Herein, we describe an overhaul of an introductory organic chemistry laboratory curriculum, informed by the strategies of meaningful learning and a desire to make the course experience mimic a research lab. This new course, primarily taught to first-year undergraduate students at the University of Michigan, is framed with three interconnected modules. We present herein the first module, which focuses on thinlayer chromatography (TLC). In the first week, students learn how to perform TLC using a variety of compounds and solvent mixtures, gaining an understanding of how intermolecular interactions affect their retention. In the second week, they practice using TLC to distinguish reagents and reaction byproducts and in the third week apply TLC to monitor reaction progress and test their hypothesis. We assessed student learning through a writing assignment at the end of the three-week module. We also assessed how the overall course affects student comprehension of TLC concepts and confidence. Our findings suggest that this learn, practice, apply approach toward teaching introductory organic chemistry laboratory concepts leads to learning gains and increased confidence.

Adapting Meaningful Learning Strategies to Teach Liquid–Liquid Extractions

“…The first-semester organic laboratory course contains three modules, with each focused on a different concept: (1) thinlayer chromatography (TLC), 35 (2) LLE, and (3) green chemistry. 36 Each module follows a similar format where week 1 is focused on learning a new skill or concept, week 2 is devoted to practicing this new skill in a new context, and week 3 involves applying what was learned to an organic reaction.…”

“…Herein, we report a new multiweek, inquiry-based LLE experiment developed within a meaningful learning framework, 33 wherein new concepts deliberately build on previously learned concepts to help students connect the new information with their previous knowledge. 34 To adapt meaningful learning for a laboratory context, we previously introduced the "learn, practice, apply" approach, 35 wherein students first learn a concept or technique, then practice that technique in a different context, and then apply the technique in an organic reaction. When using this approach to teach LLE, students showed gains in their understanding of the LLE technique and its underlying concepts, as well as increased confidence in their abilities to perform tasks in the lab environment.…”

K-5 Thin-Layer Chromatography: Three-Dimensional Analysis of Pigments from Plant Materials Using an Interlocking Building-Block Photography Box

“…20 Simple experiments, such as TLC, would help elementary students be exposed to and learn one of the central concepts taught in undergraduate level chemistry courses, chromatography. While previous experimental reports use TLC to target the undergraduate level of education, 14,21 we are building upon current frameworks to effortlessly bring the concept of chromatography into elementary school curricula. 22−25 We have designed a kid-centric activity that involves the use of interlocking building-blocks, photography, circuitry, TLC, and three-dimensional (3D) visualization.…”

“…One of the first influential reports of using TLC was by Richard Willstätter, who won the Nobel Prize in Chemistry for his discovery of chlorophyll using TLC . Since then, TLC has become a widely used teaching tool in undergraduate level chemistry courses to illustrate chromatography; one of the fundamental concepts in chemistry. − Thin-layer chromatography experiments are relatively quick to perform, safe, easy to dispose of waste, and cost-effective . Simple experiments, such as TLC, would help elementary students be exposed to and learn one of the central concepts taught in undergraduate level chemistry courses, chromatography.…”

“…While previous experimental reports use TLC to target the undergraduate level of education, , we are building upon current frameworks to effortlessly bring the concept of chromatography into elementary school curricula. − We have designed a kid-centric activity that involves the use of interlocking building-blocks, photography, circuitry, TLC, and three-dimensional (3D) visualization. We report transforming a previously used tool from a chemistry laboratory, a nerve gas detector built out of interlocking building-blocks, into a TLC photography device .…”