This paper was written by Elisha Swanson in Fall, 1999, as part an independent study course in the Chemistry Department at Bradley University. The paper contains a discussion of the pros and cons of doing chemical demonstrations in the classroom. Click here to return to the Main Demo Page.
Elisha Swanson
CHM 499
12/5/99
Just as an artist uses a paintbrush to reveal an underlying concept, a science educator uses a demonstration as his or her tool to illustrate scientific principles. In both cases, the picture is worth a thousand words. For many chemistry teachers and professors, chemical demonstrations are an integral part of their lesson planning because of their ability to promote student learning. Demonstrations can be effective in showing teacher enthusiasm, sparking student interest, initiating scientific inquiry, and displaying scientific phenomena in the classroom. Despite the many functions demonstrations can serve in the education process, some educators are apprehensive of incorporating them into the science curriculum. This reluctance is due primarily to convenience factors, limitations of demonstrations, and the consequences of misusing demonstrations. When considering whether or not to incorporate demonstrations into a teaching routine, educators should research the pros and cons of the technique and then learn how demonstrations should be implemented if they are to be effective. A conclusion one most certainly should reach is that demonstrations serve a great purpose in chemical education if they are used correctly.
Demonstrations offer many advantages that make them a valuable tool to the chemistry teacher. According to the American Heritage Dictionary, a demonstration is an illustration or explanation, as of a theory or product, by exemplification or practical application. This definition of demonstration has many applications in the chemistry classroom where educators teach chemical principles, theories, and phenomena. Demonstrations can be used to introduce or reinforce a topic in lecture by illustrating a concept, principle, or point (1). For example, when following a lecture on the conductivity of solutions, testing the conductivity of a common electrolytic solution and nonelectrolytic solution can illustrate/reinforce the role of ions in conducting a current. When the same demonstration is used as the introduction to a lecture on conductivity, student inquiry and thought processes are initiated. Students may begin comparing the properties of the two solutions until they form hypotheses on why one solution conducts a current while the other does not. The students’ observational skills are being tested just as if they were actively involved in a laboratory experiment. They use scientific thought and problem solving skills to develop conclusions. When demonstrations lead students to mentally respond in this manner, psychologists believe that the demonstration promotes higher level thinking, meaningful learning, and better retention of information (1).
Demonstrations provide teachers with a way to motivate students to learn and retain knowledge of chemistry. A chemical demonstration can focus a student’s attention and arouse student interest and curiosity in the lesson being taught. Demonstrations can reflect the teacher’s enthusiasm for the subject matter as well. Students are more likely to respond to chemistry when their teachers are excited about and focused upon the subject matter and in student learning. Because chemical demonstrations can be used to demonstrate and/or imitate real-life phenomenon, students can see the importance of chemistry in their everyday lives and learning experiences become more memorable.
Many professionals ranging from middle school teachers to college professors have devoted their studies to publishing sourcebooks on chemical demonstrations and articles supporting their inclusion into the chemistry classroom. As students of chemistry and experts on teaching chemistry, these educators have observed the effectiveness of demonstrations on student comprehension of chemical concepts and scientific thought. Bassam Z. Shakhshiri is the author of four chemical demonstration handbooks for chemistry teachers and a proponent of chemical demonstrations in the classroom. He reiterates the ability of demonstrations to teach scientific concepts and descriptive properties of chemical systems, motivate students to conduct further experimentation, and to lead them to comprehend the interplay between theory and experiment. (2). According to Henry A. Bent, recipient of the American Chemical Society Award in Chemical Education, chemistry has to be seen through lecture experiments or chemical demonstrations to be fully appreciated and comprehended:
Lecture experiments make chemical lectures demanding for lecturers, meaningful for philosophers, and interesting for students. They are highly motivational. They have immense heuristic value, tremendous rhetorical power, overwhelming persuasive force…If you don’t see it, you won’t believe it. And if you don’t believe it you won’t understand it. And if you don’t understand it, you won’t long remember it. The senses are important, not only for first discovering, but for receiving knowledge (3).
Demonstrations have been the focus of many chemical education outreach programs ran by universities and colleges. The University of Puerto Rico at Mayaquez has developed a cost effective way to train 7-12 grade science teachers and expose their students to scientific phenomena (4). Professors and undergraduate students use the demonstrations to spark interest in science which is then nurtured through small group discussions after the demonstrations are complete. Teachers were also encouraged to participate in workshops where innovative teaching techniques including the use of demonstrations were taught by professionals. Both students and teachers were required to fill out evaluation forms after each activity. Results indicated that the students’ interest in science grew as well as their desire to be involved in more "hands on" experiences and demonstrations in the future. Also, 96% of teachers replied that they would like to attend future workshops and develop demonstrations to use in their classrooms (4).
A different outreach program at Calvin College in Michigan uses demonstrations to teach chemistry lessons to elementary level students. The outreach presentations focus on uniting concepts from one demonstration to the other and relating the chemical concepts to the students’ own experiences. Although the college has not prepared a systematic evaluation of the program, over the past eight years the program has ran successfully with positive feedback from elementary teachers and students (5). The University of California in Irvine provides high school students with engaging chemical demonstrations that most high schools cannot afford the time or the money to present. This program reaches thousands of students a year and is followed yearly by positive student and teacher feedback (6). In these examples and in many other outreach programs across the United States, demonstrations are the key to educating and motivating students to learn chemistry.
Despite the amount of professional support of demonstrations and the success of chemistry education outreach programs that rely on chemical demonstrations, some educators are reluctant to use chemical demonstrations in their classrooms. This apprehension is due to a variety of factors. Convenience is one of them. For many educators the time needed to prepare, practice, and clean up demonstrations is not feasible. High cost and lack of availability of materials may also hinder a teacher’s use of demonstrations. All of these reasons are valid but can be avoided to some degree. Some of the best demonstrations are simple and direct which means they do not involve a lot of time preparing or cleaning up. For example, a great density demo requires only that an instructor place one can of regular soda and one can of diet soda upside down in a container of water. Of course, the diet floats and the regular sinks due to their difference in sugar content. This demo not only involves little time but is very feasible in terms of material cost and availability. Many demonstration resource books are available that include only household items as chemical reagents. The production of carbon dioxide gas and the exhibition of an endothermic reaction require only some vinegar and baking soda. Overhead projector demonstrations can offer a quick and easy way to demonstrate chemistry using small amounts of chemicals and minimal preparatory and clean-up time (7). Knowledge of chemistry, innovation, and creativity are sometimes all that is needed to demonstrate a variety of chemical phenomena.
Some educators feel demonstrations are a waste of time, time that is better spent in lecture covering material, or in the laboratory where students can be actively involved in chemistry themselves. Demonstrations should never replace laboratory exercises where students are actively engaged in scientific inquiry and discovery, nor should they be so frequently used that they cannot serve as a motivational tool any longer and obstruct the teaching of chemistry concepts. However, teachers may be forced to use demonstrations if time and/or the amount of resources does not permit a full student laboratory investigation. In any curriculum, in addition to chemical demonstrations, equal time and effort must be dedicated to cooperative learning and "hands on" activities, incorporating modern and relevant content, writing across the curriculum, and the use of modern media/technology and assessment techniques (8).
Whether a demonstration is used to introduce, review, or conclude a lesson, it can make a lasting impression. However, an impression should not be the ultimate goal of an educator, but a lasting learning experience. Although teachers may appear as magicians when performing chemical demonstrations, the audience should not be left merely with astonishment and amazement. The teacher must connect the abstract with the concrete and provide students with the knowledge the demonstration represents ("reveal the tricks of the trade"). If a student is left with confusion because no real connection or perhaps even a false connection between the lecture material and the demonstration has been made, the demonstration does not serve its purpose in the classroom.
Poorly conducted chemical demonstrations can be the agent of harm and are the reason learning theories suggest caution (9). Piaget’s developmental theories suggest that there are four stages in the development of knowledge. The highest level is termed the formal operational level and is characterized by the ability to go beyond observable data and familiar objects and to apply mental operations to concepts, abstractions, and theories in qualitative and quantitative ways (9). Constructivism is an educational philosophy similar to that of Piaget’s developmental theory. In constructivism, the teacher plays the role as facilitator to the individual who must use his or her senses to interpret an experience, relate the new experience to ones of the past, and then revise his or her view of experiences if one is incongruent with the other. In order for chemical demonstrations to promote a student to a higher level of thinking and reasoning consistent with these educational philosophies, a demonstration cannot be merely presented by an educator but must involve the students in the experience. Through class discussions and questioning led by the instructor, students should independently predict outcomes, offer and test explanations, and redesign prior misconceptions (9).
Modern day philosophies support the use of demonstrations as long as they are prepared, presented, and concluded appropriately. Successful chemical demonstrators employ a variety of strategies that can be divided into three categories: preparatory, presentation, and post-demonstration. When preparing to perform a chemical demonstration, one should first consider the appropriate inclusion time. Answering the following questions will aid in this decision:
What is the purpose of the demonstration and what concepts will it teach?
Where in the instructional sequence will it be most effective? And
Who is my audience and what is their prior knowledge? (10)
Choosing the demonstration that best motivates and illustrates the concept at hand will be a process of search and elimination. Other preparatory considerations include safety precautions, material preparation, and practice. When presenting the demonstration, the educator must clear the clutter from the demonstration site and ensure that the demonstration can be observed by all students. The demonstrator should introduce the demonstration in terms of material previously covered. The demonstration should be simple and direct, yet dynamic enough to spark interest and curiosity. Showmanship and humor can enhance the students’ interest in the presentation. Probing questions should be asked throughout to evoke student inquiry and problem solving. Once the demonstration is complete, the demonstrator should allow the students a few minutes to test their hypotheses and form their own conclusions. After all solutions have been proposed by the students, the demonstrator should guide the students to an understanding of the concept being illustrated. If possible, a "hands on" activity directly related to the demonstration should be initiated to reinforce the material and check for students’ understanding and application of the knowledge.
Appropriately performing a chemical demonstration may require some time and practice at first. However, as this technique is incorporated into a teaching routine the procedure will become as natural as lecturing at the blackboard. There is sufficient evidence supporting their inclusion into the classroom and a variety of demonstration handbooks that offer great ideas on how to enhance the comprehension of chemistry concepts (11). There are even references targeted at eliminating some important concerns such as time, money, and availability of materials (11). Being aware of the limitations and misuses of demonstrations is important if demonstrations are to be used effectively. However, if presented carefully and at the right time, chemical demonstrations can help convey a concept by appealing to the students’ senses in a matter of minutes or even seconds what an hour of spoken words could not communicate alone.
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