The effect of group works and demonstrative experiments based on conceptual change approach: Photosynthesis and respiration

The main purpose of our education system is to master skills that could help students to reach to the information themselves, rather than transmitting existing information to them. Furthermore, apart from memorizing, the system should improve students’ problem solving skills that they can use in a new scenario of the situation. Parallel to transmitting information to the students, the aim is to teach students about producing information and reaching the information that they will need. The expectation from current science education is a student-centered learning process with the guidance of a teacher. The teacher should be a guide that tries to understand the student’s construction of knowledge, and in some cases facilitating learning process by asking some effective questions and additionally support them by guiding students to the right resources (Gedik et al., 2002). In this learning process, information that will be learnt should be arranged one by one to create a group of interrelated information. However, students will have some previous knowledge before coming into the education environment. This previous knowledge prevents the students from reaching scientifically proved information (realities), and as a result of this, it becomes hard or even impossible for the students to gain new information. In some research, researchers consider this situation and try to find ways to reach to the desired information in the teaching and learning process by using student’s previous knowledge (Novak, 1984). New learning methods should be prepared and designed to integrate new information with his/her previous experiences based on discovery.

The Conceptual Change Approach, which is based on constructive learning theory, has frequently been used recently. It considers students’ previous knowledge and then all instructional activities are determined with respect to those considerations. In many of instructional approaches, conceptual change does not occur at all or it occurs insufficiently. This situation leads to memorization and causes misconceptions in certain subjects that need explanation, definition and estimation. For that reason, methods to overcome those misconceptions have very important role in science and technology education (Sönmez et al., 2001). One of the purposes of science and technology education is to have students learn concepts meaningfully and to use those concepts in their (daily) life (Yürük and Çakır, 2000). In order to achieve meaningful and permanent learning, misconceptions are supposed to be remediated. Misconceptions can be remediated by the revision of their previous knowledge and the modification of this previous knowledge to make it compatible with new information. This is called conceptual change process (Smith et al., 1993). This is an encouraging approach that achieves a transition from unscientific information or misconception that students’ have to information that is accepted as scientific (Chambers and Andre, 1997). In other words, conceptual change is a change process of wrong previous knowledge to true and reliable information. The conceptual change approach includes several applications. Those applications include analogies and explanatory models, conceptual change texts, concept maps, hands-on activities, information processing skills, students’ written answers, computer aided instruction, group work, demonstrative experiments and discussion.

Group work and demonstrative experiments have an important place in conceptual change approach. That is why group works and demonstrative experiments are better for students to feel out misconceptions about the subject and correct the misconceptions through questions and demonstrations (Gedik et al., 2002).

The first way to deal with student misconceptions is to be aware of them. Teachers must be aware of students’ prior knowledge and possible misconceptions. During preparation of class topics and content, teaching methods that are suitable for reducing misconceptions should be chosen. In the method of demonstrative experiments based on conceptual change, students become aware of their existing misconceptions and these misconceptions are revealed through questions and demonstrations. These demonstrations and discussions enable students to realize scientific facts and combine them with their prior knowledge. Therefore, demonstrative experiments based on conceptual change are an effective method to reduce and prevent student misconceptions (Gedik et. al., 2002). Moreover, group work based on the conceptual change approach centralizes students and makes them the explorer and constructer of knowledge; this understanding is necessary to simplify the teaching of concepts. (Çaycı et. al., 2007).

One of the most accepted conceptual change theories is proposed by Posner et al. (1982). In order for the conceptual change to take place, Posner et al. (1982) suggested four conditions are necessary: (1) students must become dissatisfied with their existing conceptions (dissatisfaction); (2) the new concept must be clear and understandable for students (intelligibility); (3) the current problem should be solved by using the new concept (plausibility); (4) similar future problems can be solved by using the new concept (fruitfulness).

The best way to understand a subject in science and technology education is to work on the subject and make connections with other science fields Turgut et al. (1997), therefore, science and technology education should accomplish integrity with other fields like physics, chemistry and biology. Especially for biology, connections and integrity of concepts have an important role in science and technology education. Therefore, biology is a more interrelated science field with respect to concepts that it covers compared to other science fields. Consequently, students have a few problems in learning concepts meaningfully, and they prefer to memorize those concepts. The most evident example of this can be seen in subject of photosynthesis and plants’ respiration. Especially in studies that were performed on photosynthesis and plants’ respiration, subjects reveal that misconceptions are very frequent (Haslam and Treagust, 1987; Tamir, 1989; Anderson et al., 1990; Amir and Tamir, 1994; Pedro, 1997; Çakıcı, 1998; Mikkilä-Erdmann, 2001; Yürük and Çakır, 2000; Alparslan, 2002; Tekkaya and Balcı, 2003; Çepni et al,. 2006; Köse et al., 2006; Köse and Uşak, 2006).

Tekkaya and Balcı (2003) carried out a study that aimed to determine the misconception of high school students on the concept of photosynthesis and respiration in plants. These researchers observed that most of the students had the idea that “photosynthesis is a gas alternation process, energy is produced after photosynthesis and photosynthesis is the reverse of respiration” which is scientifically invalid.

Çepni et al., (2006) carried out a study to reveal the cognitive development, misconceptions and attitudes of students about the photosynthesis concept. They concluded that, making use of the Computer-assisted Instruction Material (CAIM) was very crucial for attaining the application and comprehension levels of cognition in teaching photosynthesis. However, they observed that CAIM did not substantially change the misconception of students about photosynthesis.

For instance, the effect of conceptual change texts on students’ misconceptions about respiration was investigated by Alparslan (2002). As a result of this study, it was concluded that conceptual change texts were more effective than traditional approaches in misconceptions of respiration.

Köse et al., (2006) investigated the effect of concept changing texts for reducing the misconceptions of pre-service teachers in the concept of photosynthesis and respiration in plants. At the end of the study, researchers observed that most of the pre-service teachers had misconceptions about photosynthesis and respiration in plants. They concluded that, concept-changing texts were efficient in the comprehension of photosynthesis and respiration in plants and in the reducing misconceptions of pre-service teachers.

In another study, Köse and Uşak (2006) found that most of the pre-service teachers had some misconceptions in certain subjects like, “photosynthesis occurs only in green plants”, “photosynthesis is a gas exchange process”, “green plants respire only in nights when there is no light”, “respiration occurs only in the leaf of plants”. The main reasons for those misconceptions are: students’ previous knowledge, the difference of scientific jargon and daily speeches and course textbooks.

In another study, Mikkilä-Erdmann (2001) investigated the effect of conceptual change texts on understanding of photosynthesis in 5th grade students. As a result of this study, researchers highlight that conceptual change texts have an important contribution to photosynthesis; especially on the students who have insufficient previous knowledge.

Research reveals that misconception is hard to eliminate through traditional approaches because it is a permanent and continuous process, and it is not sufficient to develop right concepts on students (Tekkaya et al., 2000). Therefore, there is a need to teach pre-service teachers with effective instructional approaches to overcome misconceptions that result in meaningful learning. In this study, the use of group work and demonstrative experiments based on the conceptual change approach is used and evaluated with respect to its effectiveness in photosynthesis and plant respiration.