Understanding Of Human Circulatory System
The purpose of this study was (1) to explore prospective early childhood education teachers' understanding of selected concepts related to human circulatory system and blood circulation; and (2) to evaluate the usefulness of two learning activities for promoting participants' understanding about human circulatory system. The context of this study was an undergraduate course concerns with development of scientific and mathematics concepts and how children acquire and use scientific concepts. Quantitative and qualitative data were collected from 35 participants using two learning activities (individualized/group drawing and individualized/group response to structured questions) as an assessment tool designed to reveal participants' understanding about human circulatory system. Results indicated that three categories of alternative understanding emerged related to human circulatory system. Results also indicated that individualized and group drawing was more effective than individualized/group response to structured questions in revealing the extent of and promoting participants' understanding of human circulatory system.
Research studies dealing with students' understanding of scientific concepts have been conducted across a wide range of science topics and concepts. Most findings of these studies pointed to a fact that students hold various views about scientific concepts (Bahar, Johnstone, & Hansell, 1999; Buckley, 2000; Cuthbert, 2000; Lewis & Wood-Robinson, 2000; Reiss & Tunnicliffe, 2001; Tunnicliffe & Reiss, 1999). To date, many studies have investigated students' understanding of biological concepts. For example recent topics investigated include photosynthesis (Capa, Yildirim & Ozden, 2001; Griffard & Wandersee, 2001), ecology (Ozkan, Tekkaya, & Geban, 2004), diffusion (Marek, Cowan, & Cavallo, 1994; Tekkaya, 2003), respiration (Sanders, 1993), genetics (Tsui & Treagust, 2005), digestive system (Teixeria, 2000), and the circulatory system (Alkhawaldeh, 2007; Sungur, Tekkaya, & Geban, 2001; Yip, 1998).
Many of these investigated topics can be regarded as essential to student progression towards future biological knowledge and are interrelated. For example, knowledge about human circulatory system and its related processes are believed to be among the most critical to understanding of other biological concepts. Students' understanding of the circulatory system were found to impact their understanding of other biological concepts such as homeostasis, nutrition and transport, since circulating blood is essential for transporting needed materials to maintain favorable and needed conditions for survival. Thus students' who possess meaningful understanding of how the circulatory system works may come to understand how this knowledge is related to other biological knowledge about other systems and hence realize the important role of the circulatory system in homeostasis (Tekkaya, 2003).
On the other hand, science teachers and prerservice science teachers in particular have shown to have similar problems when it comes to scientific understanding of science. A fairly consistent portrait has been painted that illustrates preservice teachers' lack of deep content Knowledge in all science subject areas. For example, elementary and secondary science teachers have been found to hold alternative conceptions concerning science topics which are similar to the ones their students may possess, and utilize scientific terminology that they do not truly grasp (Ginns & Watters, 1995, Pelaez, Boyd, Rojas & Hoover, 2005). Furthermore, teachers were also found to possess generally low level of declarative knowledge as well as inadequate skills in the content area of science (Calik & Ayas, 2005; Jegede, Taplin & Chan, 2000; Justi &Â Gilbert, 2002; Tairab 2008).
The quality of teachers' understanding of science often tends to shape students' alternative ideas about science instead of probing for understanding. For example, findings from previous research showed that the quality of preservice secondary biology teachers' classroom discourse was greatly influenced by the quality of their content. Furthermore, other similar findings concluded that low quality content knowledge of science teachers negatively influenced their instructional strategies (Lee 1995).
Misunderstanding about scientific concepts such as circulatory system can escalate further when school teachers hold unscientific understanding. Previous research findings about the circulatory system found that both pre-service and in-service science teachers were unable to display scientific understanding about heart structure and function, blood flow, blood pressure, and blood vessels, and the relationship between structure and function of concepts associated with circulatory system and blood circulation (Yip, 1998, Pelaez, Boyd, Rojas & Hoover, 2005). Furthermore, Arnaudin and Mintzes (1985) in their early study revealed that college students too have similar misunderstandings of concepts associated with the circulatory system. For example, Arnaudin and Mintzes found that to large extent students conceptualized blood as "cells suspended in red liquid and red cells lacking an intercellular liquid". It was also found that the majority of the students at various age levels and education fail to conceive the "double circulation nature" of the circulatory system. The most frequently displayed misunderstanding at all levels was the understanding that describes the circulatory system as an open system.
Just as pre-service and college students, experienced teachers too, were found to have similar misconceptions (Yip, 1998). Although teacher education programs provide great opportunities to study instructional pedagogies, methodology, and teaching practice, few provide opportunities to deeply study science content within the framework of their teacher education programs. There is evidence that often teacher education programs spend less time on content that is closely related to school curricular (Tairab, 2008). Instead students who prepare to become teachers are often inundated with an in depth content that does not match what they will be teaching after graduating.
On the other hand, traditionally assessment approaches such as multiple-choice and written responses are commonly used to identify student alternative understanding of scientific concepts. These diagnostic tests were developed using various format including two-tire format and oral interviewing (Treagust, 1995), gathering students' written responses (Leach, Driver, Scott, & Wood-Robinson, 1995), recording students' spontaneous conversations (Tunnicliffe & Reiss, 1999) and constructing concept maps (Novak & Musonda, 1991). Evidence from research findings suggest that these approaches may not be adequate in revealing the extent of alternative understanding held by students. Alternatively, assessment and monitoring strategies are being developed by educators to help diagnose student understanding during learning processes so that students can be helped to modify their erroneous understandings. Among the alternative approach is the use of drawing and participatory strategies in a form of active student participation. The use of drawing, which relies less on words has the potential to impact the way learners assessed. Although there is a large and growing literature on the importance and centrality of language in acquisition of scientific knowledge, there are limitations to the use of language particularly when students are responding to the assessment in a non-native language.
The findings reported in this study are concerned with how participants (prospective early childhood education teachers) understand concepts related to circulatory system and blood circulation and subsequently evaluate the effectiveness of teaching activities that were used as nontraditional assessment approaches on improving understanding. This study is part of current efforts to build teachers' capacity related to the development of content and pedagogical content knowledge. The efforts, in its first phase explored how prospective teachers develop and understand concepts related to their field of study.
Although a fairly large number of studies have been conducted on elementary and secondary teachers' knowledge and understanding in science, very little is known from the literature about the scientific background of the teachers of early childhood education. Modern beliefs maintain that appropriate scientific knowledge can and should begin in infant classes (Frost, 1997). The study presented in this paper is concerned with teachers' subject matter content knowledge in the context of science in early childhood context.
This study examines understanding of prospective early childhood education teachers of selected concepts of circulatory system and blood circulation. Furthermore, the study evaluates the usefulness of two learning activities designed to assess and promote scientific understanding of participants of these selected concepts. Specifically, the study was concerned with finding answers to questions about prospective early childhood education teachers understanding of (1) heart structure and function, (2) blood circulation with its associated concepts such arteries, veins, capillaries, and blood pressure, (3) the extent to which teaching activities such individualized and group drawing as well as individualized and group response to structured questions detect and improve participants' understanding of circulatory system and blood circulation.
3. Theoretical framework
The framework for this study is based on teachers' knowledge (Lee and Luft, 2008; Loughran, Mulhall & Berry, 2008), the conceptual change theory (Duit & Treagust, 2003), and the visualization and representation theory (Gilbert, 2005). Teacher content knowledge of science is obviously fundamental to being able to help students learn. Lack of scientific understanding at a sound and a coherent conceptual level is thought to be particularly troublesome for early childhood education teachers who need to teach fundamental concepts to young learners. To communicate an accurate understanding of scientific knowledge to learners, teachers need to understand the subject matter from multiple perspectives than that actually presented to their students. To teach as advocated by most science education reforms, teachers must hold deep and highly structured content knowledge that can be accessed in a more flexible and efficient way when interacting with students. Such knowledge will be essential in order to teach for understanding and to provide authentic learning opportunities for students.
Research studies dealing student conceptions and misconceptions suggested that students need plausible and fruitful strategies if they have to experience conceptual understanding. From a perspective of the conceptual change theory, effective science teaching would have resulted in helping learners exchange their scientifically unaccepted understandings with scientifically accepted ones. A conceptual change approach suggests that if learners are to change their conceptions they must have plausible alternatives so that they become dissatisfied with their existing knowledge structure, new concepts must provide alternative viewpoints and be understandable. These new concepts must appear to apparently offer alternative solutions to problems and be believable. They must have potential for new learning (Posner, Strike, Hewson, & Gertzog, 1982). Prospective science teachers from this perspective need to develop correct, accurate, and integrated view of scientific concepts so that they develop sound and coherent content knowledge which in turn can help them effectively teach science to their students.
On the other hand, recent science education research studies have started to pay attention to the power of visual representation, drawing and modeling of scientific ideas (Ainsworth & Loizou, 2003; Gilbert, 2005). Representations, and drawing in particular, present unique challenges to learning scientific concepts. This is because representations and drawing can be used to understand student thinking and understanding of concepts' structures and functions. For example, Ainsworth and Loizou (2003) showed that diagrams and drawings elicit more self explanation than textually presented information. In visual representation and drawing learners can overcome the disadvantages posed by textual information. Furthermore, student drawings enable them to translate self-explanations across different representational format and thereby deeply depict their understanding.
The study was designed as a mixed method (quantitative and interpretative qualitative) one in the sense that it quantifies and explores how students understand concepts related to the circulatory system and blood circulation. Quantitative as well as qualitative approaches were used to collect data on participants' understanding of the concepts studied using the two learning activities. The learning activities were specifically developed to achieve two goals: to diagnose alternative understanding held by participants, and to provide them with a necessary feedback that could help them construct and develop scientific understanding of these science concepts.
The participants of this study were 35 prospective early childhood education teachers who are currently enrolled in a bachelor degree program. The participants were enrolled in a pedagogy course designed to help them understand how young children construct and develop scientific and mathematical concepts. Specifically the course was designed to enrich their understanding of children acquire and develop scientific and mathematical concepts through naturalistic and structured settings. In order to achieve these goals, prospective teachers must themselves master important scientific and mathematical concepts such as the ones under investigation. All participants were females. Participants were regarded as homogeneous in terms of ability and background judging from their college grade point average.
4.3. Data source
There were two sources for data. The source of the quantitative analysis included all participant responses to specifically developed learning activities. The first learning activities included diagram prompt method to assess participant understanding which required participants to name and label drawings related to the circulatory system and identify pathway of how blood travels to different parts of the body. The second activity includes structured questions which require participants to respond in writing.
In order to develop coherent and plausible understanding of the circulatory system learners require to link anatomical with physiological understanding, i.e. structure with function. Although the language may convey structural concepts of the circulatory system, at some level conceptual understanding need to be developed through visualization (drawings). Functions, on the other hand are much better developed through text or propositions (Mathai & Ramadas, 2009). It is suggested that combining drawing with structured questions may achieve better results in revealing both structural and functional understanding of the participants.
Participants were given diagrams of unlabelled heart structure and were asked to label the various structures that make up the heart as an organ. Furthermore, participants were given the following problem to complete.
Insert Figure 1 about here
The drawings were completed twice: individually as well as in groups. Participants completed the individualized activity first and immediately proceeded to group work before discussing their performance in individualized manners. The drawing conceptual framework was chosen as a diagnostic activity to test its effectiveness in detecting student's scientific understanding.
The second source of data was a response of structured 4 questions about the heart structure and function and blood circulation with its associated concepts such arteries, veins, capillaries, and blood pressure as in the following Figure 2:
Insert Figure 2 about here
The purpose of the structured question is to provide participants with opportunity to describe their own understanding in a more extended manner. Open responses will allow them to organize their thought and hence express their understanding in a much revealing way, and hence it will provide data to ascertain the other data generated from the drawing activity.
Each of the questions was presented to each of the 35 participants individually as well as in groups of 5 participants. Participants were probed for their reasons and explanations of their answers. The responses to the structured questions provided more clues and directions about the participants' understanding of the circulatory system and blood circulation.
The findings suggested that prospective early childhood education teachers do not possess adequate understanding regarding the circulatory system and blood circulation. Participants' understanding of circulatory system and blood circulation can be grouped into three categories of misunderstanding: Heart structure and function; blood vessels; and blood circulation.
Table 1 shows participants responses to the two activities related to the three conceptual areas of the circulatory system.
Insert Table 1 about here
5.1. Heart structure and function-
As can be seen from Table 1, 65.7% of participants showed alternative understanding as regard to naming and labeling of the main structures and parts that make up the heart individually. Participants showed inability to correctly identify structures such as valves and main vessels that should be mastered by presrvice teachers. Only few participants (34.3%) were able to correctly name and label the 10 structures that were asked to name and label.
5.2. Blood circulation
30 (85.7%) in individualized activity and 28 (80%) in the group of participants were unable to correctly draw the pathway of a drop of blood when leaving the heart to the rest of the body. Most participants were unable to grasp the idea that describes the double nature of the circulatory system where it starts from the left side chamber of the heart through the aorta to the rest of the body before returning back to the heart via the right side chamber of the heart to continue its journey to the lungs before returning back to the left side of the heart. Few participants were able to explain the concept of "Double circulation" and the role of the lungs. Typical examples of participants drawing are shown in the following diagrams:
Insert Figure 3 about here
Insert Figure 4 about here
As it can be seen from the above figure, participants expressed an understanding suggesting that blood from both left and right sections of the heart passes to all parts of the body and come back straight to the left side of the heart (Diagram 3)- an understanding that fails to recognize the double circulation nature of blood. Although Diagram 4 indicated that blood travel between right and left chambers of the heart to reflect the pulmonary circulation, it fails to include the systemic circulation. A typical correct answer explains the double circulation with blood from the left side chamber of the heart will leave to the rest of the human body and return back to the right side chamber of the heart as it complete its first cycle (systemic circulation), where it is pushed to the lungs before returning back to the left side chamber of the heart to complete its second cycle (pulmonary circulation).
Corresponding similar ideas were revealed in the writing task. When participants were asked to respond to a question in writing that asked them to describe how blood circulates to body parts, various erroneous ideas emerged consistent with the drawing activity. Table 2 presents the most common erroneous understanding among participants.
Insert table 2 about here
Typical responses were similar to the following:
"The blood is always moving. It starts from the heart and it goes around the body and it comes back again to the heart".
"The blood goes from both sides - the left and right side of the heart to all parts of the body".
"I think I see it as something like that the blood from the right side of the heart goes to the right side of the body, and blood from the left side of the heart goes to the left side of the body."
5.3. Blood vessels
Biologically speaking the structure and function of blood vessels are related. Arteries are well known by their thick and elastic walls due to their functions, while veins can easily be distinguished by their thin diameters. Participants were unable to take this into account when asked to draw a cross section of an artery and a vein. Furthermore, participants failed to recognize the direction of flow of blood in relation to veins and arteries. The idea that blood travels in veins from the rest of the body as it goes to the heart while it travels in arteries from the heart as it leaves it.
The findings also showed that 22 (62.8%) of participants were unable to differentiate between the arteries, veins and capillaries in terms of function. Only 13 (37.2%) of the participants showed basic correct responses to the questions about the veins, arteries, and capillaries, and the fact that blood travel in veins to the heart and arteries carry blood away from the heart. Furthermore, the relationship between arteries, veins and capillaries seems to be unclear to most of them.
5.4. The usefulness of learning activities:
The learning activities were found to have different sensitivities to revealing and helping participants acquire scientifically acceptable understanding. The drawing activity was found to be more sensitive to detecting misunderstanding in the three categories than the writing responses to structured questions. For example, the individualized drawing revealed most of the labeling and the blood circulation errors than the group drawing. Similarly, the individualized writing response activity revealed almost similar level of misunderstanding about blood vessel, and the relationships between arteries, veins and capillaries. As can be seen from Tables 1 and 2, Individualized activities proved to be most useful in detecting misunderstanding than group activities judging by the high percentage of errors compared to the group activity. Group activities may tend to conceal some of the most noticeable individualized errors. Generally whether individualized and group, drawings were more effective than individualized and group responses to structured questions in revealing the extent of students understanding of the heart structure and function, blood vessels, and blood circulation.
The findings of the present study suggest that prospective early childhood education teachers, just like other teachers, tended to exhibit erroneous understanding similar to those found elsewhere (Yip, 1998, Pelaez, et. al, 2005). The extent of these erroneous understandings appears high, yet the data could not confirm the exact extent which it could be even much higher than what has been revealed in this study if other diagnostic methods such as interviews were used.
The findings of this study may point to a fact that these prospective teachers need to develop a better content knowledge if they are to be effective science teachers. This is because whatever content knowledge teachers have, it directly related to their classroom practice. As shown previously research findings showed that the quality of preservice secondary biology teachers' classroom discourse was greatly influenced by the quality of their content (Tsui & Treagust, 2005; Tekkaya, 2003). It follows that teachers have to have a sound conceptual understanding of the content they teach if they are to achieve the stated curriculum and help students develop better scientific knowledge.
An important indicator that can be drawn from this study is that learning must be related to previously acquired knowledge if it has to be meaningful (Duit & Treagust, 2003). Indeed the findings of this study suggest that many prospective teachers did not possess the prior knowledge needed to develop a sound and extended understanding of human circulatory system. Knowledge of the various structures such as arteries, veins, and capillaries and their functions are necessary for meaningful understanding of the circulatory system. Indeed biological operations such as diffusion and the role of oxygen and carbon dioxide can also contribute to the development of better understanding of the circulatory system. Pelaez, et. al, 2005) suggested that "understanding cell respiration and the roles of oxygen and carbon dioxide in metabolism" most likely would help the learners develop coherence in their understanding of the interrelated nature the circulatory system with other biological processes, and hence recognize the role and function of the circulatory system in a better way.
The high level of misunderstanding revealed through the group activities suggested that participants either did not benefit from group work or they did not have the necessary knowledge to help each other. It is suggested that such ideas were more easily concealed during the group activities. The group work exposed ideas that participants were unsure about and as such these ideas seems to contradict their initial understanding shown in the individualized activities.
Based on the present findings, it would seem that the development of sound and coherent understanding of the concepts of circulatory system and blood circulation are more likely to be promoted by exposing students to varied and rich activities involving drawing and labeling and writing and reflecting experiences. Students would also benefit if relationships between the concepts and structures of the circulatory system are explicitly highlighted so that learners are able to build correct understanding related to structure and functions of these concepts.
One related observation emerges from this study is that the precise language is also required for participants to distinguish scientific concepts from everyday usage. It becomes evidence in this study that the use of the terms "circulation" may have contributed to participants not being able to comprehend the circulatory system. In the study of Pelaez, et. al, (2005) understanding of the term "circulation" was interpreted as the movement in blood in circles. And not as a systematic movement of blood through sophisticated structures in specific pathways. As the case with most misconceptions a precise use of language is very much needed to alleviate any confusion.
The results of the present study showed that the learning activities used as an assessment tool revealed a number of erroneous understandings among participants. The use of these activities suggested that the administration of such activity as drawing and labeling was highly sensitive in revealing inaccurate ideas about heart structure and function and the concept of blood circulation. The combination of a drawing and labeling and discussion and writing was also sensitive to showing confirmation of the prevalence of these erroneous conceptions among participants.
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