Lecture Demonstrations

About

If, as is often claimed, a picture is worth a thousand words, how many words might an attention grabbing mid-lecture demonstration be worth? Certainly lecture demonstrations are popular both with students and the lecturers who use them for a number of reasons:

• They provide a break enabling students to recover from the ongoing information bombardment in a typical lecture.
• Students like them and consider them fun.
• They can grab students’ attention.
• They can teach chemistry by providing concrete examples of abstract concepts.
  

There are of course also a number of barriers likely to inhibit the use of lecture demonstrations:

• The time and effort required to develop and practice a suitable demonstration. To try to use demonstrations without practicing them is a cardinal sin.
• Lack of confidence on the part of the lecturer in the suitability of their skills or personality to perform public demonstrations.
• Concerns over health and safety issues. This is probably the most serious obstacle as no benefits to learning can justify putting our students at risk. Unfortunately some of the most potentially engaging demonstrations are likely to be discarded for this reason. However, in general, with appropriate equipment and precautions most demonstrations can be performed with an acceptable level of safety, and by highlighting the accompanying risk assessments the lecturer can increase the associated learning. In extreme cases videos can be used but student opinions strongly favour actual demonstrations rather than video presentations.
  

Critics often suggest that demonstrations entertain rather than educate students but this fails to recognize that such demonstrations routinely communicate the lecturer’s enthusiasm for the topic, and tend to enthuse and motivate students to learn more about the subject area being illustrated.
Although many of us undoubtedly remember eye-catching demonstrations like the thermite reaction and adding sodium to water from our youth, George Bodner stresses that demonstrations need not be spectacular to promote effective learning. He suggests that the key requirement is that the demonstrations give rise to discrepant events, where discrepant events have two characteristic properties; they are events that we actually experience for ourselves and they are contrary to what we intuitively expected i.e. they contain an element of surprise. Students can be asked to write down their predictions of what they expect to happen, their observations of what actually happened, and then their explanation of what they have observed. This allows such demonstrations to provide an effective approach to addressing student misconceptions and promoting conceptual change.
Although significant hurdles have to be overcome, there is no doubt that well developed and presented demonstrations, in the course of a standard lecture, can improve both motivation and actual learning.

Further information and discussion can be found in the following references:  
Bodner, G. M., (2001):  Why Lecture Demonstrations Are ‘Exocharmic’ For Both Students And Their Instructors. University Chemistry Education, 5, 31-35.
Walton, P. H., (2002): On the use of chemical demonstrations in lectures. University Chemistry Education, 6, 22-27.

Original author: Bill Byers

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