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Demonstrations have been used to communicate ideas in chemistry for many years. In introductory classes they are usually presented to illustrate fundamental chemical principles and to promote discussion relating the macroscopic world of chemistry to the molecular and symbolic realms (1). The traditional demonstration/discussion model breaks the monotony of the traditional lecture format and makes the teaching experience more enjoyable. It also fosters the development of a more personal relationship between the instructor and the students and allows students to make a better connection between lecture and laboratory.
Recently we described the use of lecture demonstrations to evaluate conceptual understanding and critical thinking skills of K-12 students in physical science (2). In these "demonstration assessments" students view a short demonstration, record their observations, and explain what they observed. Rubrics are applied to score written student responses and promote class discussion. On the basis of this work, one of us (WC.D.) developed a series of demonstration assessments for freshman chemistry. The study described below was designed to evaluate the effectiveness of the demonstration assessments not only as assessment tools, but also as instruments for developing conceptual understanding and critical thinking.
Theoretical Perspective
The literature indicates that assessment and instruction are closely interrelated (3). In the current interactive model of learning in which students construct their own understanding, assessment can serve many functions in addition to evaluation of student learning following instruction. Assessment can influence instruction when it is used to discover student understanding prior to instruction. Instruction can also be influenced when assessment is used throughout the instructional process to help teachers find out what and how well students are learning (4). Embedding assessment within instruction provides feedback on learning to both the instructor and the student. Knowledge of student learning during the instructional process can help the instructor provide additional experiences that will improve student understanding. Possibly a more important function based on cognitive learning theory is the embedding of instruction within the assessment activity. According to Angelo and Cross, classroom assessment that focuses on learning is mutually beneficial (4). Students who cooperate in the assessment process reinforce their grasp of course content and strengthen their own skills at selfassessment. Demonstration assessments were designed with these student outcomes in mind.
Current cognitive learning theory stresses...