November 2014 | Nuts & Bolts
Demonstrations and Good Pedagogy
By James W. Laughner
In September, Chemical Safety Board (CSB) Chairperson Rafael Moure-Eraso’s wrote “Warning Against Use of Methanol During Laboratory and Classroom Combustion Demonstrations” in the wake of a recent museum fire in Reno, Nevada. Other similar incidents happened soon after the release of the report, and at the end of October, CSB released the safety bulletin "Key Lessons for Preventing Incidents from Flammable Chemicals in Educational Demonstrations.” Incidents like these make the news almost every year, and there are probably many more that occur that the country doesn’t hear about.
The question that comes to my mind is, “What makes these methanol demonstrations so tempting?” Teachers read these articles, so you’d think we would stop doing the demonstrations. On the other hand, teachers have very little access to scholarly articles about education. They have limited access to journals, and most likely only if they belong to an organization such as NSTA, AACT, AAPT, etc. Few teachers are reimbursed for that single membership, and school libraries rarely have funds to pay for educational journals. So maybe teachers don’t have access to all the information we should. Still, there must be more reasons why dangerous demonstrations—methanol demonstrations in particular—induce teachers to take such risks despite frequent severe accidents.
To me, the answer is not a good one. Studies have shown that demonstrations done by teachers in front of classrooms full of passive students have essentially no effect on long-term retention of concepts (1). I ask students who have watched a demonstration to tell me what it was about scientifically, and few of them can do so even one day after the demo. So if there is not a compelling academic reason, is there an affective reason for doing them? Most students remember when something impressive happens (such as a colored funnel cloud of flame, like the Reno demonstration was supposed to produce). Still, if they only remember the impressive event and not the science, who cares?
Does the interest produced by an impressive show like this aid learning by helping students realize that science is fun, interesting, or cool? Conversely, students who remember the impressive show link the show not necessarily to science but to the demonstrator: “Mr. Smith does such cool things!” This student reaction, and the lack of evidence that students retain knowledge, leads to the conclusion that teachers like to impress their students.
Teachers need to fight their egos
Rarely is good pedagogy a teacher at the front of the room telling or showing students what he or she can do. But demonstrations can work, with proper preparation and pedagogical content. For example, the physics teaching community has developed the “Socratic-Dialogue-Inducing” lab. This type of activity, over a long history of research combined with continuous effort to improve methodology, has evolved from traditional labs and demos into carefully organized, student-performed demonstrations with associated teacher inquiry and direction. The demos are called SDI labs, rather than demonstrations, which highlights the fact that the activity has moved from the front of the class to the students’ domain (2).
In general, demonstrations can be done in a way that increases both understanding and retention (3). But to properly follow that format, the teacher must specifically be removed from the front-and-center stage. After all, teachers gain content knowledge and pedagogical understanding when they do demonstrations and think about them (4); certainly students can do the same.
I have developed a number of physics and chemistry demonstrations to be carried out by students. In most cases, I modify a demonstration from one of the standard collections (5) (6). During the demonstration, a student is randomly chosen to be the “reader” and another to be the “doer.” All students start with a blank sheet of paper. They make a sketch of the equipment and take notes as the reader reads the step-by-step directions. Next, the students discuss what is about to happen. At this point, I may engage in Socratic questioning. But frankly, the best demonstrations are the ones where the students do most of the asking and answering. Finally, the reader reads the directions again slowly while the doer follows the directions. I, as the teacher, am in charge of safety first and inquiry second. I am not in charge of putting on a successful performance.
I measured the affective and content knowledge difference between this method and standard teacher-performed demonstrations over full-year periods using pre- and post-tests. One of those years I could not do SDI labs because of classroom, assignment, and schedule constraints. The difference was large, so I recommend that all chemistry teachers try SDI labs.
I share an example. It’s a methanol demonstration, but it does not use bulk quantities, so it fits the new methanol guidelines. I wrote it many years ago after an incident similar to the recent one in Reno made the news in California. It uses methanol specifically to show the effect of intimately mixed gases and the dangers inherent when a reaction is started between them. Methanol is NOT used just to make a demonstration more “showy.” Given the recent notices, however, it is worth mentioning that isopropyl alcohol (95%, not 70%) can replace the methanol if container volumes and liquid quantities are adjusted (I use about 7 mL of isopropyl in a 1-L container). Whichever liquid is used, the teacher must check for safety, including evaluating the plastic container, performing the demonstration carefully without students, and checking recent literature for safety and other suggestions.
(1) Crouch, Catherine, Adam P. Fagan, J. Paul Callan, and Eric Mazur. "Classroom demonstrations: Learning tools or entertainment?" American Journal of Physics 72, no. 6 (2004): 835–838. DOI: 10.1119/1.1707018.
(2) Hake, Richard R. "Socratic Pedagogy in the Introductory Physics Laboratory." Physics Teacher 30, no. 9 (1992): 546–552. DOI: 10.1119/1.2343637 (see also: http://hakesedstuff.blogspot.com/2012/07/move-physics-demonstrations-from.html).
(3) Laughner, James W. "Student-Led Demonstrations: How and Why." Journal Of Virginia Science Education 1, no. 1 (2006): 45.
(4) Clermont, Christian P., Joseph S. Krajcik, and Hilda Borko. "The influence of an intensive in‐service workshop on pedagogical content knowledge growth among novice chemical demonstrators." Journal of Research in Science Teaching 30, no. 1 (1993): 21–43. DOI: 10.1002/tea.3660300104.
(5) Bilash, Borislaw, George R. Gross, and John K. Koob. A Demo a Day: A Year of Chemical Demonstrations. Flinn Scientific, Inc., 1995.
(6) Shakhashiri, Bassam Z., ed. Chemical demonstrations: A handbook for teachers of chemistry. Vol. 3. University of Wisconsin Press, 1989.