Undergraduate and masters students' understanding about properties of air and the forms of reasoning used to explain air phenomena

Purpose of the Research
This study has three purposes: (a) to examine the content knowledge of preservice teachers (undergraduates) and inservice teachers (masters students) on physical properties of air, (b) to assess the effects of hands-on centers and discrepant event demonstrations in clarifying incomplete understandings or misconceptions, and (c) to analyze the forms of reasoning used while observing demonstrations or engaged in hands-on experiments.

Subjects and Context
The study subjects were undergraduate and master's students majoring in elementary education at a large, urban, southern American university. They were from two undergraduate cohorts with 27 and 31 students, respectively, and a master's cohort with 21 students. Most of the undergraduates had taken a two-course biology lab sequence as their science requirement. The research was conducted in undergraduate and graduate science methods courses. While taking the course, the undergraduates were in their junior year and were in field placements two days a week. The master's group had just completed an alternative certification program with an urban focus and was in its first year of teaching in urban schools. Their program was designed for people with an undergraduate major in a field other than education, and some of the students had not enrolled in science courses since high school. Thirteen of the master's students and 44 of the undergraduates (16 from one cohort and 28 from the other) had complete data sets and were included in the study. In this study, the subjects will be referred to as preservice and inservice teachers or simply as students.

Assessment Instrument
A test on air phenomena was developed by Bulunuz in 2002, while working with middle school students’ conceptions on physical properties of air, and was revised with input from the second author (a science education professor), and an environmental engineer. The test consisted of 14 items addressing conceptual understanding of the following general properties of air: that it occupies space, exerts pressure, expands when heated, and has lower pressure when flowing (Bernoulli's Principle); and knowledge of the composition of air, the relationship between altitude and air pressure, the effects of change in air pressure on the boiling temperature of water, effects of partial vacuum, and effects of no air (such as on the moon). Pretests were administered before a class session on air pressure demonstrations and hands-on activities. Posttests were administered several weeks after the session. Neither the pretest nor the posttest counted toward the students’ grades. The questionnaire’s content validity was established with input from a scientist and a science educator. To determine reliability of the questionnaire, a convenience sample of one undergraduate class of 22 preservice elementary teachers answered the questionnaire two times, two weeks apart. For each student, the answers to each question on the two administrations of the questionnaire were compared, and the percentage of identical answers was calculated. Across the 22 students, the mean percentage of questions answered the same both times was 78%.

Instructional Intervention with journaling
The intervention consisted of class sessions in which students engaged in 17 hands-on center activities and watched 6 discrepant event demonstrations. The sessions took most of two 2 ½ hour classes, one week apart. Most of the activities were taken from Liem (1989). They had been implemented with Turkish middle school students (Bulunuz, Jarrett, & Bulunuz, 2009) and also with adults at a convention workshop (Bulunuz, Bulunuz, Jarrett, & Hoge, 2004). The demonstrations mainly involved fire or heating and illustrated the effects of heating and/or cooling on air volume. They were done as demonstrations to model safety precautions. Some of the activities and demonstrations are described in Appendix A. The activities and demonstrations covered four physical properties of air included in the air properties test: air occupies space, air exerts pressure, Boyle’s law, and the Bernoulli Principle. For each activity, students answered questions in their dialogue journals, making predictions and giving explanations of the phenomena they were observing. To ascertain what forms of reasoning were used by the students, 10 student journals were randomly selected for analysis of the reasoning used to explain the air phenomena involved in 11 of the activities. The 11 activities represented two or three activities for each of the four concepts. The authors categorized the explanations into phenomena-based reasoning (PBR), relation-based reasoning (RBR) and model-based reasoning (MBR), as defined by (Driver et al., 1996). Descriptions of the 11 activities and correct model-based explanations for each are found in Appendix B. The first author and a colleague analyzed the journal entries independently and the percent of agreement was calculated as 96%.