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Teaching with Technology
Gabriela C. Weaver Purdue University West Lafayette, IN 47907
Discovery Videos: A Safe, Tested, Time-Efficient Way To Incorporate Discovery-Laboratory Experiments into the Classroom
W
Lyubov Hoffman Laroche CUST, Department of Education, University of British Columbia, Vancouver, BC V6T 1Z4, Canada Gary Wulfsberg* Doctor of Arts Program, Department of Chemistry, Middle Tennessee State University, Box 405, Murfreesboro, TN 37132; *
[email protected] Barbara Young Department of Educational Leadership, Middle Tennessee State University, Murfreesboro, TN 37132
How frustrating it can be to read the Journal of Chemical Education! Its pages are full of innovative ideas, but a seasoned teacher all too often realizes that he or she is not going to have the time, or sometimes the opportunity, to implement those ideas in daily teaching. Sadly, the fate of many of the ideas developed in this Journal is to remain on the pages, never to be widely disseminated into classroom practice. Constructivist educational theory (1, 2) emphasizes the importance of students confronting and wrestling with observations and data, then constructing their own understandings of the principles behind that data. This is commonly done in inquiry-based or discovery-laboratory experiments (3). But some courses have no laboratory periods or the periods are short. Some reactions that a student should experience prior to concept construction are too hazardous to be carried out by inexperienced students or in labs with limited hood capacity. Hazards are reduced if instructors demonstrate the hazardous reactions, then the students discuss (in small groups) and draw conclusions from the demonstrations. Perhaps a “minds-on” approach by students to chemical experiments does not require “hands-on” experience. Demonstrations can result in injuries and take a lot of time (and some space) to prepare. In 1996 the National Academy of Sciences set new science education standards that strongly advocate inquiry-based, hands-on education in science (4). As states have implemented their own requirements for inquiry-based laboratory experience, more serious accidents have occurred (ca. 50% more in Iowa; ref 5) as experiments or demonstrations are carried out in inadequate facilities or under the supervision of instructors with inadequate safety preparation (more than 55% of Iowa secondary-school teachers have never received safety training or received it more than 10 years ago; ref 6 ). In the past we have advocated principles to predict and explain many of the practically limitless number of observations and facts that comprise descriptive inorganic chemistry (7, 8, 9a). In previously published textbooks (8, 9) we included a set of six or seven discovery-laboratory experiments (3) that instructors could assign before the principles were introduced in the textbook, so that students could “discover” 962
these principles themselves. Many instructors have used these experiments quite successfully, but many others do not have laboratory times allocated to their courses. In the instructor’s manuals associated with these textbooks (10, 11), we have suggested ways, during 50-minute lecture periods, of doing these demonstrations with students in small-group discussions leading to the “discovery” of the principles. This paper focuses on two of these demonstration–discussions: “Some (Acidic) Reactions of Cations”, during which students observe the (sometimes violent) acidic reactions of metal cations with water and discover the relationship of a cation’s acidity to its charge, size, and electronegativity; and “Periodicity in the Activity Series of Metals”, during which students observe the (sometimes violent) reactions of metals with acids and water and discover the relationship of this activity to the Pauling electronegativity of the metal. These demonstrations, involving reactive materials such as TiCl4(l) and sodium metal, are time-consuming to prepare, taking up to 4.5 hours to get ready, and they generate hazardous fumes, HCl(g) and H2(g), in classrooms that often do not have appropriate or functioning hoods. Modern educational technology offers many ways of presenting images of chemical reactions to students. Students in small groups should be able to confront the images on a screen and discuss them until they “discover” a concept or a pattern of periodicity. Recent literature includes examples and evaluations of the use of computer simulations (12, 13) and Web-based tutorials (14) in discovery learning. It has been shown that the particular technology used to present information does not significantly affect the resulting learning (15). However not all forms of educational technology are equally available in classrooms and not all are equally instructor friendly: some forms take much time for instructors to set up, or learn how to use them. Hence we wish to report the use of a very simple, widely available medium, videocassettes in a VCR, in a freshman honors-level general chemistry course and a junior–seniorlevel inorganic chemistry course. These videos not only show images of hazardous reactions, but also give instructions to organize students into groups, think about the data, draw
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their conclusions, and design the next part of the experiment, all within 50 minutes. We have applied the standard qualitative and quantitative methods of chemical education research to verify that the quality of learning from the videos compares with that from the much more instructor time-consuming live demonstration–discussion presentation. There have been earlier reports of the use of videos in instruction, involving an unspecified type of discussion (16) that gave a statistically significant improvement in student performance. Recently Whisnant (17) has placed a series of 32 general chemistry videos on a CD-ROM. The program asks students questions about the experiments and allows students to request additional video information. Unfortunately, no assessment of the effectiveness of these videos was included. Video- and Demonstration-Based Group Learning Activities Two video-based lessons were filmed in which the author demonstrates the reactions as he would in front of a live class. Before the demonstrations, the video asks the students to organize themselves into small groups to create hypotheses based upon their prior knowledge, experiences, and information provided to them. These hypotheses are to predict how they think the reactivity to be demonstrated relates to periodic trends in the size, charge, electronegativity, or ionization energies of the elements or cations to be tested. Scripts of the videos are included in the Supplemental Material.W WorksheetsW are provided for recording hypotheses and predicting the order of reactivity of the elements or halides that would subsequently be tested. A copy of the worksheet is turned in to the instructor before the demonstration begins; students also keep a copy of the worksheet so that they can compare their predictions with the data. Sets of demonstrations are then presented on the video (i.e., in the cation-acidity video, the widely varying reactions or nonreactions of LiCl, ZnCl2, AlCl3, and TiCl4 with water; in the activity-series video, the reactions or nonreactions of 11 metals with cold water). Students are asked to record and turn in conclusions as to the type of periodicity exhibited in each set (i.e., more highly charged cations, such as Ti4+, react more violently with water). A set number of minutes is allocated on the video to accomplish this task, but the instructor can use the pause or the fast forward button on the VCR to change this as needed. When all groups have turned in logical conclusions, the video gives the next set of reactions; the instructor may choose to give a bonus point to the first group to “publish” a logically defensible explanation of what they have observed. This sequence is continued until all demonstrations have been completed. With the activity-series video, students are then asked to plot a graph of the standard reduction potentials of the metals (a quantitative measure of reactivity) versus the atomic property that they hypothesized would correlate most closely with the activity. Then, unless they happened to predict that activity would most closely relate to Pauling electronegativity, they see that they have a graph with a lot of scatter. In this case, they may revise their hypothesis and confirm it graphically. The graph or graphs are turned in to the instructor, along with a statement as to whether their original hypothesis has been confirmed or refuted. After the video is completed, the instructor may discuss why the most logical
hypothesis—activity should relate to ionization energy—does not work well (8b) and then discuss the possible reason why the Pauling electronegativity gives the best correlation (9c). In the second part of the cation-acidity video, students observe the reactions of PCl3, SbCl3, and BiCl3 with water and generally conclude that increasing “cation” size reduces reactivity (acidity). But in the third part of the video, the nature of the task is changed from discovery learning to problem solving (3): students are asked to design an experiment to test the effect of electronegativity on cation acidity, using only two or three of 11 halides that are suggested. Student groups turn in a worksheet suggesting which two or three halides should be tested and why. This endeavor turns out to be challenging even for senior chemistry majors, since they have to remember to control, not one, but two variables (cation charge and size): as many as half of all groups fail to remember to do this. Several sets of halide combinations are reasonable answers; the video demonstrates the reactions of the most colorful pair, BiCl3 and PCl3. The theory of why cation acidity should depend on charge, size, and electronegativity is left to be developed later in the text and the lecture; the students are not asked to discover this theory. Peterson (18) emphasizes that educational materials should be lively, dynamic, and as intriguing as television, music, videos, movies, and computer games; humor and sound effects in particular contribute greatly to stimulating students’ imaginations. These videos have incorporated music written by students from MTSU’s Recording Industry Management program, humor, films of scenes, and cartoons and digital animation for illustration of electronegativity, ionization potential, and other abstract concepts by L.H.L. Quantitative Assessment of the Videos To determine whether discovery learning based on videos represents a viable alternative to discovery learning based on live demonstrations, we utilized a crossover experimental research design. The class of 28 junior–senior-level inorganic chemistry students was divided into two groups, A and B, each of which was subdivided into teams of 3–4 students. During the first lesson (on cation acidity, relatively early in the course), group A was taught by L.H.L. via video at a separate location, while group B was simultaneously taught by G.W. in the regular classroom using a live demonstration. For lesson two (on the activity series, taught near the end of the term), groups A and B switched modes of instruction, locations, and instructors; a total of 22 students (8 males and 14 females) completed both lessons. Students of both groups were tested the following day, then again on the midterm or final exam. The complete set of questions is included in the Supplemental Material.W One set of four different questions focused on direct recall of observations; for example, “Briefly describe what happened when TiCl4 came into contact with water in the first part of the demonstration or video.” Another set of six questions focused on recall of the principles learned or discovered; for example, “What did your team conclude was the periodic tendency shown in the first part of the demonstration (or video) by the four cations coming into contact with water?” A third set of nine questions required the students not only to recall the principles, but to apply them to situations that were not observed in the video or
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demonstration; for example, “Which of the following metals (rubidium, beryllium, platinum, cadmium) is least likely to dissolve in a hydrochloric acid solution?” Finally, the success of construction of six principles as shown on the worksheets was compared. The mean percentage scores and their statistical analyses are summarized in Table 1. The statistical analysis (ANOVA for Latin square crossover design) of exam scores indicated no significant differences in students’ abilities to recall the observations, recall the principles, or apply the principles to new situations between the video-based discussions or the live-demonstration discussions. In every case, the scores for video-based instruction tended to be slightly higher and the result for applications of concepts to new situations was near to the alpha level, p = .05. The differences, however, were statistically insignificant, which is not surprising given the small sample size and given the results of previous chemical education research (15). Qualitative Assessment of the Videos For qualitative assessment of videos versus live demonstrations in the junior–senior-level course, an open-ended questionnaire format was used to explore the students’ perspectives. The complete set of handwritten responses is available as a thesis appendix (19). Student responses were analyzed using comparative-pattern analysis (20): responses were categorized by two competent judges from the MTSU Department of Educational Leadership, neither of whom was involved in the lessons. The first question asked was “What were the strengths and weaknesses of the audiovisual presentation of chemical reactivity trends?” Four categories each of strengths and four of weaknesses were identified by the judges. The strengths and some representative comments are:
VW2. Method of presentation: “not real life presentation”, “experiments were not carried out in real life”, “with video it is difficult to get the full effect of reactions”. VW3. Speed of presentation: “video seemed to go too fast”, “camera moved too fast”, “video went much too fast”. VW4. Clarity of presentation: “reactions weren’t quite easily seen”, “was difficult to see”.
The second question was “What were the strengths and weaknesses of the live demonstration presentation of chemical reactivity trends?” Three categories of strengths and four of weaknesses were identified by the judges. The strengths and some representative comments follow. (In part, the responses labeled DS1 are the converse of the VW1 responses, and DS2 is partially the converse of VW2): DS1. Ability to interact with the teacher: “we were able to ask questions”, “could ask questions”, “can ask: what about, what if ”. DS2. Method of presentation: “it is live, it is real”, “clear sense of real life applications”, “experiments being carried out in real life”, “getting to actually see the reaction taking place”. DS3. Organization of the lesson: “well-organized”, “easy to understand”.
The weaknesses and some representative comments follow. (In part, DW1, DW2, and DW3 are the converse of VS1, VS2, and VS3, respectively.) DW1. Interest: “exciting”, “didn’t have the visual effects to hold my attention”. DW2. Self-access: “can not go back and rewind”, “if you missed it, it’s over”, “if you missed one part, you are lost”.
VS1. Interest: “interesting”, “exciting”, “impressive”, “capturing attention by effects”.
DW3. Safety: “the vapors were nasty”, “more chance of personal injury”.
VS2. Self-access: “ability to rewind”, “can control”, “can replay and freeze”, “possibility to check out”.
DW4. Difficulties to view: “not everyone can get a good look at the reactions because of seating arrangements”, “inability to all class to view”.
VS3. Safety: “no hazard”, “got to see more dangerous reactions without fear”. VS4. Organization of lesson: “very well organized, well written”, “a lot of material in concise form”, “correct amount of time”.
The weaknesses and some representative comments are: VW1. Ability to interact with the teacher: “no one to ask questions”, “can’t ask questions”, “inability to explain if it is not clear”.
The third set of qualitative questions asked students “Which method of presentation did you prefer: video or demonstration? Which method did you learn more from? Why was this?” Fifty percent of the students preferred the video method and 50% favored the live demonstration method. Fifty-seven percent declared that they learned more from the live demonstrations, 33% declared they learned more from the videos, and 10% declared that they learned equally from both.
Table 1. Mean Percentage Scores for Different Learning Activities According to the Method of Instruction Learning Objective Construction of concepts on worksheets
Mean for Videos (%)
Mean for Live Demonstrations (%)
F
p
61.5
56.3
F(1, 6) = 0.14
0.72
Recall of visual observations
79.5
77.2
F(1, 34) = 0.07
0.92
Recall of principles
81.8
78.8
F(1, 34) = 0.10
0.62
Application of principles to new situations
75.5
60.6
F(1, 34) = 2.88
0.08
Mean score on 19 questions
74.7
70.5
F(1, 34) = 1.68
0.21
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We noted that the student responses on learning better from live demonstrations apparently conflicts with the observed higher scores on quizzes and exams for students using videos, but one must keep in mind the statistical insignificance of the differences. The comments under VS2 (self-access) represent flexibilities of the method but were not possible in this particular class, since only the instructor controlled the VCR and the videos. The comments under VW1 (ability to interact with the teacher) were true in this particular class owing to time limitations, but are not intrinsic to videos used by instructors in sessions that have more time available. The comments under DS3 and VS4 show a split in opinion on which presentation was more organized. Finally, it was not possible to complete the entire live demonstration lesson on the activity series in the time available, whereas this was possible using the video. Use of the Videos in Honors-Level General Chemistry Course With the ease of use of the VCR approach, the two instructors of MTSU’s honors-level general chemistry classes now use these video-based lessons with freshmen during laboratory periods, which removes the time constraint. In this lower-level course, the specific observations and concepts are not nearly as important as the chance for students to practice the scientific method by evaluating data and reasoning inductively to conclusions. In this class the activity-series video was used near the end of the first semester as a practical illustration of the utility of the abstract concept of electronegativity, while the cation-acidity video was shown the second semester during the study of acid–base equilibria. Honor-level classes at MTSU never exceed 20 students, so that splitting the class between live demonstration and video would have resulted in very small populations for statistical purposes. Because there is considerable change in student population between semesters, the crossover method used in the larger inorganic course could not be repeated in this course. Thus we were limited to less rigorous methods to evaluate the results. Over a three year period we asked the students to reflect on the discovery video and other laboratory experiments: “Please describe the major good features and bad features of the...lab experiment.” and “What is the main thing that you learned and remembered from each lab?” These reflections were mailed in anonymously and typed by a student worker; they are given in the Supplemental Materials.W This author (a biased judge) found the students’ reflections to be generally very favorable. Particularly at the freshman level, it appears that students highly value multidimensional representations of instruction (animation, music, acting, arts) along with their active involvement in the process of knowledge construction, and the competitive aspects of trying to be the first group to make scientific “discoveries”; there were only a few comments mentioning safety. The videos were appreciated as a change of pace from the usual lab experiments. The videos or the demonstrations have been used in high school settings, where they may be appreciated more for their value in safe and interesting instruction in the scientific method rather than for the specific chemical principles developed. We have made no study of this usage.
Conclusions Many instructors have stopped doing demonstrations as a result of time constraints and would welcome a video alternative to use for presentation purposes. A number of the students in our teaching-oriented Doctor of Arts degree program (21) are full-time, small-college or community-college teachers and may have to teach as many as five courses per term; they enjoy learning about chemical education innovations but know that they will never have time to implement most of them. We feel that this consideration is true even for professors in research universities, who must publish or perish. Four hours or more might be required to set up each live demonstration before doing it in class; however, it is easy to put a video into a VCR. Simpler is better if educational innovations are actually to be adopted widely in high schools, colleges, and universities. We have used standard quantitative and qualitative educational research methods to determine that no harm is done in taking the timesaving and video approach to discovery learning involving hazardous reactions. Our analysis of student test questions based on recall of observations, principles “discovered”, and ability to apply these principles to new examples showed no statistical difference between students using lessons based on videos versus those based on live demonstrations of chemical reactivity. The qualitative research showed no significant difference in student preference for either method of instruction, although there appear to be some tradeoffs of strengths and weaknesses. The videos were first used at the inorganic level to teach principles of periodicity in metal-ion acidity and metal-redox activity, but since they also teach inductive reasoning from scientific evidence, hypothesis generation and testing, graphing, and experimental design, we have also used them in an honors-level general chemistry course. We believe that the videos have potential use in secondary-school science teaching as well, especially when there is not much time available for experiments, when the teacher is not satisfied with his or her training in chemistry or safety, or when the facilities are not adequate for safe demonstrations. We do not wish to advocate the routine use of discovery videos to replace laboratory experiments of modest hazard done in labs with adequate hoods under the supervision of instructors with adequate safety training. As a result of this research, we have personally abandoned the time-consuming, live demonstrations using hazardous materials and have ever since used the videos. We will be happy to provide copies of the videos and the worksheets to anyone who writes to G.W., sending one blank videocassette on which the two videos can be recorded. These videos will be available on JCE Online as part of JCE WebWare and the JCE Digital Library project. Acknowledgments We specifically wish to thank Sandra Smith and B. James Hood for assistance in the chemical education aspects of this project; Amy Phelps for her helpful comments; Pat Jackson and Ken Byers of the Television Section of our Audio兾Visual Services Department for assistance in filming and editing the videos; and Marc Barr of the Electronic Media Communication Department for assistance with the digital animation.
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Supplemental Material
Instructions and scripts for the video demonstrations, quiz and exam questions, and honors-level student responses to the questionnaire are available in this issue of JCE Online. Literature Cited 1. Brooks, J. G.; Brooks, M. G. Honoring the Learning Process. In Search of Understanding: The Case for Constructivist Classrooms; Association for Supervisory and Curriculum Development: Alexandria, VA, 1993. 2. Caprio, M. W. J. Coll. Sci. Teaching 1994, 2, 210–212. 3. Domin, D. S. J. Chem. Educ. 1999, 76, 543–547. 4. National Science Education Standards; National Academy Press: Washington, DC, 1996. 5. Grelovich, J.; Wilson, E.; Parsa, R. J. Iowa Acad. Sci. 1998, 105, 152–157. 6. (a) Gerlovich, J.; Parsa, R. Science Teacher 2002, 69, 50–55. (b) Gerlovich, J.; Parsa, R.; Frana, B.; Drew, V.; Stiner, T. J. Iowa Acad. Sci. 2003, 109, 61–66. (c) Webber, T. School Science Labs Are Often Experiments in Danger. Los Angeles Times, July 7, 2002. 7. Wulfsberg, G. J. Chem. Educ. 1983, 60, 725–728. 8. Wulfsberg, G. Principles of Descriptive Inorganic Chemistry; Brooks-Cole: Monterey, CA, 1987; pp 415–427. 9. Wulfsberg, G. Inorganic Chemistry; University Science Books:
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Sausalito, CA, 2000; (a) pp 927–939. (b) pp 323–325. (c) p 336. 10. Wulfsberg, G. Instructor’s Manual for Principles of Descriptive Inorganic Chemistry; Brooks-Cole: Monterey, CA, 1987; pp 50–52. 11. Wulfsberg, G. Instructor’s Solutions Manual for Inorganic Chemistry; University Science Books: Sausalito, CA, 2000; pp A.1– A.6. 12. (a) Robinson, W. J. Chem. Educ. 2000, 77, 17–18. (b) de Jong, T.; van Joolingen, W. R. Rev. Educ. Res. 1998, 68, 179–201. 13. Sanger. M. J.; Phelps, A. J.; Fienhold, J. J. Chem. Educ. 2000, 77, 1517–1520. 14. Parrill, A. L.; Gervay, J. J. Chem. Educ. 1997, 74, 329. 15. Clark, R. S. Educational Technology Research & Development, 1994, 42, 21–29. 16. Enger, J.; Toms-Wood, A.; Cohn, K. J. Chem. Educ. 1978, 55, 230–232. 17. Whisnant, D. M. J. Chem. Educ. 2000, 77, 1375–1376. 18. Peterson, G. A. Good Education and Good Entertainment; National Geographic Society: Washington, DC, 1990. 19. Hoffman, L. Design and Evaluation of Effectiveness of Audio–visual Discovery Lab Experiments in Teaching Inorganic Chemistry. M.S. Thesis, Middle Tennessee State University, Murfreesboro, TN, May 1996. 20. Patton, M. Q. Qualitative Evaluation and Research Methods, 2nd ed.; Sage Publications, Inc.: Newbury Park, CA, 1990. 21. Mason, D. J. Chem. Educ. 2001, 78, 158–160.
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