Research into an inquiry-based heat and temperature curriculum.
Abstract
This paper includes quantitative and qualitative analyses of the success of the heat and temperature curriculum as taught by Torrey Newcomb at Seattle Preparatory School.
Introduction
Students in
Pretesting was used to determine student understandings of the subject prior to instruction. Students were directed
in their completion of a photocopied packet of experiments, questions, and directed analysis, which constitutes the bulk of their
curriculum. Posttesting determined student understanding of the subject after the instructional period. The material for the pretests,
packet, and posttests is drawn, with few changes, from curricula developed by the Physics Education Group at the
In the final analysis, the new curriculum's use (by the same, but more experienced teacher) at Seattle Preparatory was successful. Student understanding of heat and temperature was found to be improved over the students' understanding prior to instruction, but less than complete. New clarity in the teacher's goals, a more extensive and more clear curriculum, and better preparation in the new year enabled a very different classroom experience than had occurred in the previous year.
Method & Results
Pretest
Pre- and posttesting and a rigorous comparison of correlated tests can illuminate the effectiveness of the heat and temperature curriculum in three ways. The pretest isolates alternative preconceptions in order to determine whether the curriculum is successful in redirecting student thought; the appearance of those incorrect or misapplied concepts in the post-test is an indicator of curricular effectiveness. The pretest is useful in determining the extent of students' prior instruction in the topic matter, in order that the successes of previous instruction are not included in the success of this curriculum. The post-test is a showcase for the students' new understandings, and a forum for persistent preconceptions to be aired. The appearance of correct answers and reasoning on the posttesting instrument is a third indicator of curricular success.
The first pretest asked the students about the relative temperatures of two blocks of identical size. One block is made of aluminum, the other of wood. Both blocks have been in the same room, undisturbed for one year. The correct answer to the question is that they are at the same temperature, because they have reached thermal equilibrium with the rest of the room. To answer correctly, students must have at least an intuitive understanding of thermal equilibrium. To express correct reasoning, students must be able to explain or name the phenomenon.
Pretest Results
Descriptions of the phenomenon of thermal equilibrium in pretest one were recorded by the researchers as thermal equilibrium responses. 25 students (14% of 177) who used this type of reasoning gave correct answers. Student responses such as "No one has done anything to either of them [the blocks]" (student 296) and "…because they are both subject to the same outer temperature and therefore will have the same inner temp" (student 299) were recorded as thermal equilibrium-based reasons.
The vast majority of students (60%) used incorrect reasoning based on the nature of the materials in question. For example, students stated that aluminum attracts, reflects, absorbs or conducts heat, so its temperature would be different from the wood in the same room. Density was another property of matter perceived to affect the temperature of objects. Students using property of matter criteria did not answer the question correctly.
Instruction
The heat
and temperature curriculum researched is taught as part of the Physical Science course at
Specific goals in heat and temperature were centered on three areas: laboratory skills, analysis skills, and topical understanding. Students were to learn Bunsen burner use and safety, examine and use thermometers, and make precise measurements of volume and temperature. Analysis of the collected data required students to use numeric and graphic analysis tools, such as proportional reasoning, trends, and slopes. Student understanding of topics within heat and temperature was another of the educational goals, but the focus of the course is on developing science skills rather than building physics knowledge.
The students spent a total of eighteen class periods (usually 40 minutes long) in their study of heat and temperature. They were given a 21-page packet, (Appendix A) which was their guidance through the material. The packet contains instructions for observations and procedure, and questions to guide the students' analyses of their data. Several all-class discussion sessions elicited and directed student thought. On occasion, "mini-lectures" introduced scientific terminology for concepts the students had already encountered. Students were familiar with the class structure: they worked in partners or four- to five-person table groups, and were directed toward daily goals (e.g., "Let's get through section 1.8 today.") Occasionally, students finished packet sections as homework. Assessment included a review of completed packet work, two quizzes, and the observations of the teacher.
Posttest
Question 2B of quiz one tested the students' ability to apply their understanding of thermal equilibrium. Students were presented with a block of aluminum suspended in boiling water, and asked to predict the temperature of the aluminum. Students were expected to answer that the aluminum was the same temperature as the boiling water. The anticipated reasoning was an explanation or name of the phenomenon.
The students had two conceptual difficulties about question 2 that they asked during testing. The diagram of the aluminum in boiling water showed the aluminum halfway out of the water, causing students to wonder about the effect of room-temperature air on the temperature of the block. Students who asked were directed to ignore any effect air might have on the block's temperature. The diagram should be improved in future testing to depict the block as completely submerged. Students also had concerns about the length of time the aluminum had been in the water. Inquiring students were told, "long enough," or "for a while," which were answers that seemed to satisfy them. The question could be modified to include a statement of duration to avoid those concerns.
Posttest Results
Researchers used a finer comb when investigating post-test 2, question b. Only students who used the phrase "thermal equilibrium" were recorded with the thermal equilibrium response, in order to isolate differences in language that may reflect other thinking. Student responses are best characterized by the phrase, "… because of thermal equilibrium." (Student 217, among many others.) Simple use of a phrase does not indicate understanding. However, because all students (35 students, or 43% of 81) who used "thermal equilibrium" in their reasoning gave correct answers, we can assume a close correlation between use of the phrase and the students' understanding of it.
Many students who did not use the phrase "thermal equilibrium" also showed understanding of the phenomenon by describing situational reasoning in which the temperature behavior of thermal equilibrium is implicit. For example, one student responded, "Because the water stays at 100°, the aluminum will heat to 100° also." (Student 294) Another student: "…because it would become the same temperature as the boiling water." (Student 215) They show in these statements an application of the concept without identifying the concept by name. Therefore, students responding with this type of reason to achieve the correct answer (7 students, or 9% of 81) are included in the pool of students who understand the concept of thermal equilibrium.
The diagram shown in the post-test is misleading, so that some students who understood thermal equilibrium gave incorrect responses. Six students wrote that the block is only partially submerged in the water, so its temperature was dependent on the environment outside and inside the beaker. Some student responses: "…because part of it is out of the water therefore in thermal interaction with the boiling water and also the air witch[sic] should be a lower temperature then the water" (student 262); "the aluminum is only half way in the water so heat will be transferred from the top… the aluminum will have temperal equalibrium[sic] with its surroundings" (student 270); "…because it is only half way in and not totally submerged it is probably around 60°C to 70°C" (student 285.) These students show a clear understanding of the phenomenon at hand; they merely used misleading visual information that was unintentionally given to them by their teacher. These students (7% of 81) are also added to the pool of students who have demonstrated understanding of thermal equilibrium.
Student responses that included the idea of heat transfer are difficult to categorize. Statements such as, "Heat is the energy transferred from one object to another and the heat in the water is transferred to the aluminum and therefore they are the same" (student 247) leave researchers with the knowledge that the student understands that the objects are in thermal interaction, but do not demonstrate deeper understanding of equilibrium. Similar statements, such as "…because it has been heated with the calories the water has given it" (student 204) and "…because when a heat transfer happens, the objects are interacting. So the boiling water has to distribute its heat evenly to the objects its interacting with." (student 281) illustrate the same difficulty. Because every student who used this kind of reason answered correctly, it is probable that some of the students responding understand thermal interaction. They may simply choose to describe the phenomenon in terms of heat transfer; unfortunately, it is impossible for these researchers to determine how many of the 15 students (19% of 81) using this type of reasoning understand thermal equilibrium.
Only three (4% of 81) students used reasoning based on properties of the aluminum. The persistent preconception is that aluminum attracts heat. Students employing this idea still answered correctly, which may lead one to suspect that they are simply too disorganized to correctly state their internal knowledge. However, incorrect reasoning belies the truth: regardless of their ability to answer the question, they credit aluminum with powers beyond reality.
Conclusion
Quantitative Assessment
Students showed marked improvement in their understanding of thermal equilibrium. Only 14% of students correctly described the phenomenon in the pretest. 60% of students correctly used the concept of thermal equilibrium in posttest responses. An additional 19% of students utilized reasoning that may indicate understanding of thermal equilibrium. In total, at least 46% of the 81 students posttested reveal concept acquisition following instruction.
Students are not aware of all of the differences between the concepts of heat and temperature. Data collected indicates that about half of the students recognize that objects in thermal interaction will come to the same temperature. One fifth of students choose to use descriptions of heat transfer in their explanations, which leads this researcher to suspect they closely interrelate, and confuse, heat transfer and temperature change.
Qualitative Assessment
Pre and posttests ask students to apply their knowledge; in a less formal setting, a teacher may simply ask a student to explain a concept or phenomenon. Students who can apply the concept will carry the concept away with them; students who can merely describe a concept will perhaps only have the seed of understanding planted within them. This teacher strives for many levels of learning: student assessment is based on both application and description.
Conversations with students revealed to the teacher two key facts in the teacher's determination of the success of this heat and temperature curriculum. One: students correctly describe the phenomenon of thermal equilibrium, including its requirements for objects to be in contact and at different temperatures. Evidence for this can be found even within the difficult heat transfer reasoning on posttest question 2B: "…because when a heat transfer happens, the objects are interacting" (student 281). Two: students are certain that heat is not the same thing as temperature. They may not be sure why, or how, but they can recognize and give examples of heat transfer as different from temperature. Three individual students from the classes each have been observed while explaining to their classmates that the heat transferred to one object can produce a temperature change different than the same heat transferred to another object.
The students do not have a clear and complete understanding of heat and temperature. Their curriculum, the limited time spent on the material, and the difficulty of the concepts presented together prevent them from a full realization of the physics they investigate. A complete understanding of heat and temperature for these students is not a reasonable expectation, given these circumstances. Many incorrect student preconceptions are addressed and successfully corrected, and students develop and are given correct physical information. Students leave this curriculum with a partial understanding of heat and temperature, and a method for further investigation.
The intent of this course, and this curriculum as part of the course, is to plant the seeds of scientific interest while developing students' capacity for scientific thought. Therefore, the curriculum is successful.
There are improvements that can be made in the curriculum to incrementally improve student understanding. More time and work can be spent on heat transfer, to cement in student minds the distinguishing characteristics between heat and temperature. Change of state could be re-explored to illustrate heat transfer without temperature change. Perhaps if students spent more time with heat capacity and specific heat, they would understand them better. The major requirement for curricular changes is time: more time in the classroom, and a greater percentage of student time and attention. Time is precious in the classroom; it is unlikely that more time will be afforded to this one subject.
The teacher has difficulty containing her enthusiasm for the students' performance in the course this year. Students took responsibility for their own learning. They showed great enthusiasm when given the opportunity to use their burgeoning skills. The topics within heat and temperature are exceptionally challenging; students' understanding is hampered by colloquial use of scientific terminology, as is assessment of that understanding. When those frustrations mounted, students worked to overcome the difficulties with varying degrees of success. Still, their pervasive feeling of success was infectious. Each of the course goals is reflected by requirements of the heat and temperature curriculum, and every goal has been met.