Research: Science and Education
Chemical Education Research
edited by
Diane M. Bunce The Catholic University of America Washington, D.C. 20064
Understanding of Elementary Concepts in Heat and Temperature among College Students and K–12 Teachers Paul G. Jasien* and Graham E. Oberem Departments of Chemistry and Physics, California State University San Marcos, San Marcos, CA 92096-0001; *
[email protected] Concepts associated with heat and temperature (H&T) are prevalent throughout the science curricula at all levels of elementary, secondary, and post-secondary education (1, 2). Because of this, a number of studies (3–7 ) and teaching aids (8–12) at various levels have dealt with students’ understanding and concept development in these important topics. A perusal of typical introductory chemistry or physical science textbooks at the college level shows that elementary H&T ideas are introduced relatively early. In first-year chemistry courses, this introduction is followed by related concepts such as heat capacity and specific heat, work, enthalpy changes in chemical and physical processes, and the laws of thermodynamics. The microscopic model of temperature, as a measurement of the average kinetic energy of atoms or molecules, is usually introduced as well. When the more complex ideas of thermodynamics are introduced during introductory courses, it is generally assumed that students have a firm grasp of the elementary ideas of thermal equilibrium and heat transfer. It is furthermore assumed that these ideas become more firmly rooted in the students’ content knowledge the more they are exposed to them. This paper reports on a study of the understanding of elementary concepts related to H&T in undergraduate and post-baccalaureate students as a function of their number of semesters of college-level physical science training—specifically, their understanding of thermal equilibrium and energy transfer in the form of heat. Since these ideas are prerequisites for understanding the more complex concepts related to thermodynamics, they may serve as a barometer for the framework that students bring to the study of more advanced topics related to H&T. In addition to thermal equilibrium, selected ideas related to specific heat, heat capacity, phase changes, and their graphical display are investigated. Procedure All data were obtained through surveys administered by the authors or designated class instructors. Strict adherence to a standard set of instructions was maintained for all groups. Anonymity of the respondents was assured at all times and individuals’ names were never associated with a particular survey. The survey itself consisted of 4–5 pages. The first page requested relevant background information on the participants. This was followed by three pages of multiple choice questions relating to H&T. The full text of the survey and quiz are given in Appendixes A and B, respectively. Only questions 1, 3, 4, and 5 from the quiz are discussed in detail here. Early in this work we determined that question 2 on phase transitions was ambiguous; however, it was retained for consistency.1 Also, a subset of students was given an open-
ended question that required interpretation of a temperatureversus-heat-input graph. This question will not be discussed in this work. Thirty participants who were in-service middle- and highschool physical science teachers took a slightly different version of the quiz given in Appendix B; it contained the same four major questions examined here but had a number of different questions that related to H&T. This slight difference in the test did not lead to significant differences in the overall results when the two groups were compared. Data were analyzed using the SPSS 6.1 software package for the Macintosh.2 In most cases a χ2 analysis with α = .05 was performed to determine statistical significance of the results (13). Tests on data with one degree of freedom (2 × 2 case) using the χ2 test are corrected using the Yates correction for continuity (14 ). For both of these analyses, statistical significance is claimed when the value of p is ≤.05. Additional analyses were performed using ANOVA (14 ) for cases that generated interval data. Study Population The individuals surveyed came from various groups with diverse backgrounds in the physical sciences. Student participants came from a number of courses at a four-year public institution (California State University San Marcos, CSUSM) and a four-year private institution (the University of San Diego, USD). These respondents were divided into groups based upon the number of college-level physical science courses they had completed plus those in which they were currently enrolled. These groups are designated S1 (one semester), S23 (two or three semesters), and S4 (four or more semesters) to indicate the number of semesters of physical science taken. About one-half of the CSUSM student respondents were enrolled in undergraduate courses that included the first semester of general chemistry, the second semester of algebrabased general physics, and two upper-division biology major classes. The other one-half were post-baccalaureate students, designated as CRED, in the teacher credential program of the College of Education at CSUSM, who were seeking to become K–8 teachers in California. Participants from the credential program group were included both in groups dependent on the number of semesters of physical science (S1, S23, S4), and also as a separate category (CRED). This was done to obtain additional information on the general science background of prospective teachers. The individuals in the CRED group made up 42%, 61%, and 33% of the S1, S23, and S4 subgroups, respectively.
JChemEd.chem.wisc.edu • Vol. 79 No. 7 July 2002 • Journal of Chemical Education
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Research: Science and Education
All the students from USD were enrolled in the second semester of organic chemistry at that institution. This group is designated ORG. All of these students had a traditional one-year sequence of general chemistry and various amounts of physics. Since the USD organic students represent a different demographic group in terms of age and educational background, they are not included with the CSUSM students in terms of semesters of physical science, but form their own group. However, since this group is most closely related in terms of background in physical science to the S4 group from CSUSM, it provides a consistency check on the generality of the results for students who have had four or more semesters of physical science. The last group surveyed was in-service middle- and highschool physical science teachers from the southern California counties of San Diego, Orange, and Riverside. These teachers were participating in an NSF-sponsored summer physics course taught at CSUSM (NSF ESIE-9731367). Their teaching experience ranged from one to 30 years. This group is labeled IOP, for Inquiry-Oriented Physics, the name of the project. It may not be representative of the general population of middle- and high-school physical science teachers, since the participants self-selected to attend the summer physics course. The information in Table 1 gives background data on the participants in this work. As can be seen, the ages of the participants spanned a wide range. Since USD tends to have a more traditional student body, the age range of that group was quite different from that of the students from the comparable CSUSM S4 group. CSUSM has a higher average age owing to the large number of returning students and the fact that about one-half of the CSUSM students sampled came from the fifth-year teacher credential program. In terms of gender, the majority in all groups were female. All groups were predominantly made up of individuals whose native language was English. No further investigation of whether language or gender was a barrier to performance on the content questions was pursued. The data in Table 2 give the results for the groups’ “perceived understanding” of concepts in H&T. Perceived understanding represents how individuals rate their understanding of the scientific ideas of heat and temperature. It is a very subjective measure. Very few of those surveyed (.22, indicating no significant differences. For the groups with one semester of college-level physical science (S1*, CRED1), p values for questions 1, 4, and 5 were .16, .04, and
