Design and Evaluation of Integrated Instructions in Secondary-Level Chemistry Practical Work

摘要

Practical work in secondary-level chemistry laboratories involves a high cognitive load for students. In addition to reading and understanding instructions, students have to think about observations and the underlying chemical concepts, as well as deal with the noise and social interaction of a busy classroom. One form of extraneous cognitive load in practical instructions is the split-attention effect, whereby students have to continually switch their attention between apparatus diagrams and the written instructions. This article discusses the development, use, and evaluation of instructions that integrate apparatus diagrams with simplified textual and pictographic instructions. Four practical tasks were designed and evaluated: distillation of a crude oil substitute, properties of crude oil fractions, synthesis of copper sulfate, and pH and neutralization. Data were collected on students' and teacher's classroom experiences with the instructions, and students' learning was assessed after the practicals. In general, students found the practicals easy to complete, liked the clarity of the instructions, needed to ask few practical-related questions during the tasks, and mostly gave at least partially appropriate answers to postpractical questions on what they had observed and done. Integrated instructions provide a potentially useful method for reducing students' cognitive load and increasing their confidence and understanding during practical work.