THE COMPARISON OF CONTENT SEQUENCES ON UNDERSTANDING OF CHEMICAL SUBSTANCES FOR THE UNIVERSITY FRESHMAN
STUDENTS Tuğba YANPAR ŞAHİN*
Baki HAZER** ABSTRACT
The comparison of inductive and deductive content sequence of the concept of chemical substances has been studied. Inductive content sequence was ordered in the structure of atom and periodic table, chemical bonding, intermolecular forces and properties of liquids and solids and chemical substances, while deductive content sequence was reverse. This research was applied on 74 freshman students in 1999-2000 spring terms. The students were equally divided in to two groups which one of the group took chemistry course in deductive content sequence and the other group took inductive content sequence. Science process skill test, multiple choice test and essay type test were applied on these students. Observations and interviews with some students were also made during the course. The data obtained from the tests were analyzed with Multivariate analysis of Variance (MANOVA). After the completion of the content sequence, the students who took the course in inductive content sequence, achieved better than students who took the course in deductive content sequence on essay type test results. Additionally gender resulted not significant on dependent variables. Observations and interviews results indicated that inductive content sequence had positive effect on the students.
Key Words: Content Sequence, Teaching of Chemical Substances, Chemistry Education
ÖZET
Bu çalışmada kimyasal maddeler konusunda tümevarım ve tümdengelim içerik yaklaşımları karşılaştırılmıştır. Tümevarım içerik sırasında atomun yapısı ve priyodik tablo, kimyasal bağlar, moleküller arası çekim kuvvetleri, sıvı, katı ve gazların özellikleri ve kimyasal maddeler üniteleri sırasıyla işlenirken, tümdengelimde tam tersi bir sırayla üniteler işlenmiştir. Bu araştırma 1999-2000 güz döneminde 74 öğrenci ile yapılmıştır. Bilişsel işlem beceri testi, çoktan seçmeli test ve yazılı sınav kullanılmıştır. Gözlem ve görüşmede yapılmıştır. Veriler MANOVA istatistiği ile analiz edilmiştir. Yazılı sınava gore gruplar arasında anlamlı farklar bulunmuştur. Gözlem ve görüşme sonuçları tümevarım içerik sırasının tümdengelime gore öğrenciler üzerinde daha pozitif etkisi olduğunu göstermektedir.
* Yrd.Doç.Dr. Zonguldak Karaelmas University, Ereğli Faculty of Education, Kdz. Ereğli ** Prof.Dr. Zonguldak Karaelmas University, Ereğli Faculty of Education, Kdz. Ereğli
Anahtar Sözcükler: İçerik sırası, Kimyasal maddelerin öğretimi, Kimya eğitimi
1. Introduction
Different characteristics influence students learning. One of these characteristics is the sequence of content that can effect students learning. Content is one of the components to curriculum. Parker and Rubin (1966 in Ornstein and Hunkins 1988) have noted that when educators speak of content, they refer “to the compendium of information which comprises the learning materials for a particular course of a given grade”. This information may consist of “facts, laws, theories, and generalizations” as in the case of mathematics or science courses, or it may consist of “a description of events” trends or categories, as in the case of a history course. Content is a compendium of facts, concepts, generalizations, principles and theories similar to disciplined knowledge (Ornstein& Hunkins 1988 :205).
Content can be organized in order to experience the concrete first, then the more abstract. This psychological factor is a key principle of sequencing content. Most educators assume that content can be organized by going from the students’ immediate environment to a more distant environment (Ornstein& Hunkins 1988:207). Inductive and deductive approaches are two of the varying methods of content organization (Armstrong 1989). According to inductive approach, the content of the subject matter is sequenced from particular concepts to general concepts. On the other hand, according to deductive approach the content of subject is organized from general concepts to a particular concept. Deductive reasoning is generally described as moving from general principles to a particular phenomena. Inductive reasoning (or induction) is generally described as moving from particulars to general principles (Williams 1998).
When one of us (B.Hazer) was a student in third class chemistry course of junior high school, he had an experience on first chemistry lesson: “our chemistry teacher was giving a reaction between sulfuric acid and sodium hydroxide. I have never forgotten how I memorize this reaction without realize any of it. So I was wondering what SO4 means, what H2 means, What is NaOH? How do they handle these NaOH, H2SO4 molecules? How do they write molecular formulae while they react just substances. If they had started, from the atom to substance, I would have understood very well this reaction. Because of this, I always wondered the effect of the order of the topics, deductive or inductive”. This work was carried out to solve this wonder.
This study is related to the content of the general chemistry course on the freshman students at the elementary teacher education. In teacher education programs there are three parts of lectures. Pedagogical lessons
(curriculum, etc.), subject matter lesson (chemistry, mathematics, etc.) and general cultural lessons (Literature, etc.). General chemistry course covers the subject matter in the elementary teacher education programs in Turkey. In inductive content sequence, the units were ordered in the structure of atom and periodic table, chemical bonding, intermolecular attractions and properties of liquids and solids, and matter. In other words, inductive content sequence in this study initiated from sub-microscopic nature of the atom. In deductive content sequence, units initiated from macroscopic substance and followed chemical formulas, properties of liquids and solids, intermolecular forces, chemical bonding and structure of atom. In chemistry, the concept of chemical substances is very important as a central to the content and pre-requisite to the following concepts. Meaningful learning of this concepts by the students will determine their cognitive and affective characteristics. While considering sequence, Taba (1962) has noted that sequence of content should be based on the logic of the subject matter. Taba (1962) also advocated that teachers take an inductive approach to curriculum development starting with specifics and building to a general design and noted selection and organization of content in her models. A teacher just cannot select content but must organize it in some type of sequence, taking into consideration the maturity of the learners, their academic achievement and their interest.
Studies comparing the effectiveness of inductive content sequence to deductive content sequence on students’ achievement aren’t common in science education literature. Sakmyser (1974) compared the effect of two learning sequences on high school students’ achievement to teach chemical equilibrium. Although neither deductive nor inductive program was significantly more successful other factors including ability in algebra and reading affected the success of the students. Students with high achievement scores on reading test performed significantly better on the deductive program than those who had low scores. On the other hand, students with high scores on the algebra test were significantly more successful on the inductive program than the students with low scores. Other studies related to inductive and deductive methods are mostly concerned with instructional methods rather than content organization (Herman and Hinckman 1978; Tobias 1973; Yore 1984; Hall 1976)
Chemical concepts need to be taught in different contexts (Nieswandt 2001:159). It is widely accepted that students can interpret, organize, and structure knowledge into their cognitive structure as interrelated concepts with the help of what they have already known (Sungur, Tekkaya, Geban 2001:93). The concepts of atoms, periodic table, chemical bonding, intermolecular forces and properties of liquids and solids, and chemical substances are the basic concepts of general chemistry. These concepts are heavily related to the other concepts of general chemistry. Therefore, meaningful understanding of these concepts by the students will determine
their achievement on following concepts of general chemistry. According to the literature review meaningful learning occurs when a learning task is related to what the learner has already known (Ausubel 1968). The student makes an intellectual link between the newly learned material and that previously stored in his or her cognitive structure. In this process prior knowledge affects the meaningful learning (Glasersfeld 1984; Bodner 1986). Science courses of large, introductory collage are often designed in such a way as to allow students to remain passive and anonymous (Burdge, Daubenmire (2001:295). Sequence of content can effect learning processes for meaningful and active learning. In general chemistry course, there is a controversy on the chemical substances sequence. Some books start from chemical substances, some other books start from atomic structure. From this point of view, the main purpose of this study is to compare the effectiveness of inductive and deductive content sequences which are related to organization of knowledge on students’ achievement based on chemical substances.
2.Method Subjects
This study was conducted with 74 freshman students of a general chemistry course in 1999-2000 Spring terms. This course was a part of a four-year teacher education program for the preparation of elementary school teachers. The chemistry class was randomly divided in two groups based on inductive content sequence which begins from atoms and ends to chemical substances; and deductive content sequence which begins from chemical substances and ends to atoms. One of the groups consisted of 37 students was instructed by deductive content sequence. On the other hand, the other group consisted of 37 students was instructed by the inductive content sequence .
Design and Procedure
A pretest-posttest experiment-control group design was used in this study. The course was scheduled as 3 hours in a week. The study was conducted in the first 6 weeks of 14 weeks instruction. The same instructor (B.H.) having more than 25 years of experience has taught both of the inductive and deductive groups in two years. This study was confined to the general chemistry course consisting of four units. The contents of the units were as follows:
Unit I: Structure of atom and periodic table: Dalton’s atomic theory, discovery of electrons and protons, X-ray and radioactivity, electromagnetic radiation, quantum theory, Bohr atom theory, modern quantum mechanics,
quantum numbers, writing the electronic structures of atoms and ions, periodic table, atomic and ionic radius, electronegativity.
Unit II: Chemical bonding: Metallic bond, ionic bond, covalent bond, covalent bond theories, valence shell theory and hybridization, properties of covalent bond, dipol moment.
Unit III: Intermolecular forces and properties of liquids and solids: Intermolecular forces, dipol-dipol attractions, H-bondings, and London forces. Gases, liquids, changes of states, vapor pressure, critical point, phase diagrams, liquid crystals, glasses, solid crystals, and determination of crystal structure.
Unit IV: Chemical Substances: atomic weight, mole concept, empirical and molecular formula, ions, oxidation numbers, chemical formula, naming compounds, balancing chemical equations, chemical yield, and excess of reactant.
Although the content of the subjects studied in each group was the same, the content of the subjects was given in the reverse order to each group. The inductive group followed the order of the units I, II, III, and IV, while the deductive group studied in reverse, from the unit IV to unit I.
The same textbook (Hazer, 1997) and teaching materials (eg. projector) were followed in both the classes. In addition, same examples were given to both groups. Students’ participation was mainly in the form of listening, taking notes and sporadic questioning. The instructor solved both algorithmic and conceptual problems in both groups.
Throughout the treatments, three observers (a chemistry expert, a curriculum developer and a science educator) observed both groups in order to ensure that the instructor implemented the study as intended. Some observations were recorded. After the treatment, interviews were made with the lecturer and the students.
Before the treatment, a 40-item multiple-choice achievement test and science process skill test were administrated to both groups as pre-test. After the treatment, multiple choice achievement test and essay type achievement test were implemented as post-test to both groups.
Instruments:
Multiple-Choice Achievement Test
In order to investigate students’ achievement about the four units, a 40-item multiple choice achievement test was developed by the researchers.
While developing this test, the instructional objectives for the four units in different cognitive levels (knowledge, comprehension and application) were stated by the researchers. Each item of the test had one correct answer and four distracters. The items of the test were investigated by two experts in chemistry, a chemistry educator and a curriculum developer for face and content validity. The test was given to both groups as pre-test (MCPRAT) to examine students’ prior knowledge before the treatment. There was no significant difference between two groups before the treatment. Moreover, the same test was administrated to both groups as post-test (MCPOAT). The reliability ( KR-20) of the test was found to be 0.84 in 1999 on the sample the other group . SPSS program was used on computer.
Essay Type Achievement Test
10 essay type items covering the concepts of four units were constructed by an expert in chemistry according to the instructional objectives. The test included questions for investigating students’ conceptual understandings and problem solving abilities. The test was controlled by a professor in chemistry and a curriculum developer for face and content validity. A detailed scoring key, which showed each step in solving questions and acceptable responses, was prepared. The test was scored by the chemistry expert according to the scoring key. The test was administered after the treatment.
Science Process Skill Test
In order to analyses students’ science process skills including identifying variables, identifying and stating hypotheses, operationally defining, designing investigations and graphing and interpreting data, Science Process Skill Test (SPST) developed originally by Burns, Okey, and Wise (1985) was used. The test was translated and adopted into Turkish by Geban, Aşkar and Özkan (1991). It consist of 36 four-alternative multiple-choice questions. SPST was given to both groups before the treatment. The reliability (KR-20) of the test was found to be 0.85 in 1999.
Analysis
The data analyzed by multivariate analysis of variance (MANOVA) which is a statistical technique for statistically equating groups on one or more independent variables. Moreover, means and standard deviations were given for all independent and dependent variables. Also, observations and interviews examples are given in this study for discussion.
3. Results
Prior to treatment, independent t test were employed to determine whether statistically significant mean difference existed between two groups with respect to science process skill and prior knowledge (multiple choice prior-achievement test). Statistically no significant mean difference was found between two groups with respect to science process skill and multiple choice pre achievement test (p>0,05) indicating that students in the two groups were similar regarding these two variables.
Descriptive Statistics
Dependent variables are multiple choice post-test achievement (MCPOA) and essay type test achievement (ETTA). Independent variables are group and gender. The means and standard deviations of the variables results are listed in Table 1. Both inductive and deductive groups had 37 students. On the other hand, means of ETTA scores were different significantly ( Inductive group mean: 53.78, deductive group mean: 43.35). Inductive group ETTA means higher than deductive group ETTA means. MCPOA means of inductive group 8.51, deductive group 8.84.
TABLE 1. The Result of the Descriptive Statistics on The Freshman Students Taken Chemistry Course
Variable Group N (Student Number) Mean St.dev. Inductive 37 8.51* 5.35 MCPOA Deductive 37 8.84* 6.66 Inductive 37 53.78** 17.87 ETTA Deductive 37 43.35** 20.35
*Scores were evaluated out of 40 **Scores were evaluated out of 100
MCPOA: Multiple Choice Post- test Achievement ETTA:Essay Type Test Achievement
Multivariate Analysis ( MANOVA )
All of the descriptive variables were used for MANOVA statistical analyses.
In order to test the effect of independent variables on dependent variables MANOVA analysis was used.
Assumptions of Manova are multivariate normality, independence of observations and homogeneity of covariance matrices. As assumption of Manova , all the individual dependent variables were normally distributed, and a subject scores on the dependent measures weren’t influenced by the
other subject in his or her groups. In addition, Box’s test of the equality of covariance matrices met the assumption of MANOVA. These results were presented in Table 2.
Table 2 shows that Box’s Test of equality of Covarience Matrices tests the null hypothesis that the observed covariance matrices of the dependent variable are equal across groups (p>0,05, sig:0.06 ). Thus, the data satisfy the homogenity of covariance matrices assumption.
The data set meets the assumptions of the Manova.
TABLE 2. The Results of The Box’s Test of equality of Covarience Matrices
Box’M F Dfı Df2 Sig
.149 1.912 9 52769 .06
The Manova model for the study consisted of 2 dependent variables which are students’ multiple choice post-test achievement and essay type test achievement. The independent variable included in the model were group and gender. Table 3 presents the multivariate test of this Manova Model.
TABLE 3. The Results of The Multivariate Test of Manova Sources of
Variance Hotellings Lambda Hypothesis df Error df F Sig.
Gender .021 2 69 .728 .486
Group .091 2 69 3.135 049*
Gender*Group .125 2 69 4.328 .017*
*sig. 0.49 and 0.17 < 0.05
As seen in Table 3, group and group*gender resulted in significant Multivariate F( Group F: 3.135, sig.: 0.049; group*gender F: 4.328, sig.: 0.017). This means that there was a significant difference between students exposed to deductive content sequence and students exposed to inductive content sequence on the dependent variables of their multiple choice post- test achievement or essay type test in order to decide which dependent variables were responsible for this significance the follow up tests of between subjects effect should be investigated.
Table 4 presents the result of tests of between-subjects effect for dependent variables. As can be seen from the Table 4 the group resulted in significant F for only essay type test achievement (Group ETTA F: 0.83, sig.:
0.02; gender*group ETTA F: 6.26, sig.: 0.02) and there is no significant for multiple-choice post-test achievement. ETTA means were different in two groups. Inductive group students’ mean of scores were significant higher than the other group. In addition, gender resulted not significant on dependent variables.
TABLE 4. The Results of The Between -Subject- Effects
Source Dependent Variable Squares Sum of df Square Mean F Sig.
MCPOA 6.33 1 6.33 .18 .67 Gender ETTA 377.52 1 377.52 1.11 .30 MCPOA 3.42 1 3.42 .10 .76 Group ETTA 1988.33 1 1988.33 .83 .02* MCPOA 140.24 1 140.24 3.96 .051 Gender*Group ETTA 2135.57 1 2135.57 6.26 .02* *sig.0.02, p<0.05
Results of Interviews and observations
As a result of the tape recorded interviews, instructor told that deductive groups hadn’t comprehend each content by self unless whole subject had been completed. For example, in last chapter Chemical Substances in case of inductive content sequence groups, students were able to explain the meaning of 2 in K2SO4 (e.g. abstracting are valence electron, oxidation numbers of potassium is one) on the time. It can be said that deductive content sequence group students just memorized what means of 2 in K2SO4. Because of their lack of this explanation; they tried to solve the problems on chemical substances in Chemical Substances chapter without learning basic concepts.
The instructor indicated that “I am surprised there has been positively change on the inductive group student’ s attitude and interest by the time”. The four students selected in inductive group according to different achievement scores of the examination said that “ Many of us were first confused but later we were used to the lessons and were able to participate actively and ask questions when we needed. This lesson was useful for our understanding of chemical substances”. Four students in deductive group told that “we were able to solve the problems. But we learned some concepts needed for substances later”. Some students in both of the groups indicated that “our lecturer gave examples from daily life, he solved problems and helped us for our understanding the topics in chemistry. We asked questions….”. This shows that a democratic classroom was constructed during the teaching- learning process in these groups. So, there was no big and significant difference between inductive and deductive content sequence groups.
The observations and interviews in inductive group indicated that a lot of the students had grasped the chemical concepts. But the other group students couldn’t grasp the chemical concepts sufficiently. They were able to solve the problems. But they couldn’t explain chemical concepts, in detail.
4. Discussion, Conclusion and Suggestions
The main purpose of the present study was to investigate the contribution of a sequence of content approach accompanied by inductive and deductive content sequence to freshman students understanding of the chemical concepts. It was found that there was no significant difference between to groups regarding their chemistry knowledge before the treatments. Also, there was no significant difference between two groups regarding science process skill. Therefore determination of the similarity between students in the two groups before the treatment.
During the treatment, in inductive content sequence groups, students learned from sub- microscopic atom concept to macroscopic substances concepts. These concepts were related. The students in inductive group were understanding concept of atom and nature of atom, they learned new topics and solved problems chemical substances easily. On the other hand, deductive content sequence group students learned from macroscopic substances concepts to sub- microscopic atom concepts. In deductive group, students solved problems on chemical substances firstly. But for example, they could not explain electronegative score’s means of substances, they just memorized it.
The achievement effectiveness of inductive and deductive content sequences on chemistry students was studied by multiple choice test and essay type test. The results of the study indicated that there was no significant mean difference between groups exposed to inductive content sequence and deductive content sequence on multiple choice test achievement. But there was significant difference between groups exposed to inductive content sequence and deductive content sequence on essay type test. In essay tests, the students explanations and solutions have been very clearly observed.
In Turkey, generally high school students learn chemical substances first in chemistry which means deductive content sequence. In our opinion, this can not be suitable for the high school students. Inductive content sequence can be better to give chemistry knowledge. From this point of view we have performed this study. However, we have seen that there’s no big difference in learning chemical substances in the order of inductive and deductive content sequence but during the deductive content sequence course, these students absolutely do not understand how to realize chemical formulas, walens electron and stoichiometry of the chemical reaction. Each contents
separately memorized by students instead of understanding of the idea until whole chapters were completed. In contrary, students can wonder how to built formulas after first chapter and throughout the lecture during chemistry course student attraction can continue.
Different content sequence didn’t effect the students achievement on multiple choice test. It can be said either inductive or deductive content sequence can be used for teaching in chemistry. However, observations and interviews with instructor and students and result of essay type test indicated that the inductive content sequence student might have been able to recognize the relationship between the subject of the units while constructing general object on the specific subjects. In inductive content sequence in this manner, students could easily show the relationship between concepts in essay type questions. On the other hand, in deductive content sequence students might have had difficulties in establishing relationship among the subjects in their cognitive structures. So, in the beginning, chemistry course was very boring for deductive group. Interactions were different in this group. The result of the observations showed that the students in inductive group were reluctant to participate in the earlier stages of the lesson in the beginning of this study but later their participation had changed dramatically. The students were asking more questions, more willing to solve problems. And; the students in this group were able to explain how and why to solve the problems and meaning of the concept and generalizations. So, they participated learning- teaching process in class. Researchers in the domain of science education frequently describe concept learning as a process of conceptual change (Boxtel, Linder, Kanselaar 2000). Student’s conceptual development therefore consists of a variable mix of introduction of new facts and concepts; weak restructing of existing conceptions, and strong restructing of existing conceptions. Students simply capture or add new information to their previous conceptions (Harrison, Grayson, Treagust 1999). Prior-knowledge affects new learning. Inductive content sequence students used prior-knowledge in this study. For instance, students used structure of atom, periodic table and ionic bonds for understanding chemical substances. While developing chemistry programs, curriculum developer and teacher should be aware of that chemical concepts have to be repeated often and in sequencing contents and that students need a variety of opportunities to practice the new concepts at similar tasks as well as to apply them related phenomena. Inductive content sequence group students used sub-microscopic chemical concepts often for macroscopic chemical substances. Therefore, students can understand these concepts. Teacher candidates (subjects in this study) can be taught chemistry courses by giving inductive content sequence (microscopic concepts to macroscopic concepts related one another). In addition, this content sequence can be used with active learning- teaching approaches. Inductive content sequence can provide meaningful learning on chemical substances.
The limitations of this study were: data collection was belong to the result of total units however, other studies in same and different content areas should be conducted to compare unit to unit with the effectiveness these two content sequence. After whole chemistry course finished, whichever method followed, the students learn chemistry very well. Questions related to the each subject in their mind, find answer gradually as lecture continue. In summary, qualitative results of this study showed that inductive content sequence can provide meaningful learning on chemical substances. Further research in this area is necessary in order to develop appropriate curricula for the introductory chemistry courses which foster students’ successful and meaningful learning of basic chemistry concepts.
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