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Asia-Pacific Forum on Science Learning and Teaching,Volume 16, Issue 1, Article 6 (Jun., 2015) |
Design
The experimental research was conducted to develop conclusions regarding the causal impact of an intervention by comparing a treatment group against a control group (Borg, Gall & Gall, 1993, p. 298). As summarized in Table 1, this study was based on the pretest-posttest control group design. This experimental design involved two matched groups, which were randomly designated the treatment and control groups. Both groups were administered a pre-test, received different educational programs and were administered a post-test.
Table 1. Design of the research study
Groups
Assignment
Pretests
Treatment
Posttests Treatment
Random
AA
SPS
ATSEDifferentiated
AA
SPS
ATSEControl
Random
AA
SPS
ATSEGeneral
AA
SPS
ATSENote. AA: academic achievement; SPS: Science Process Skills; ATSE: scale of attitude toward science education
Participants
The participants in the study consisted of 21 gifted 5th-grade students between 10 and 11 years old attending a primary project school affiliated with Istanbul University and the Ministry of National Education located in Istanbul, Turkey. Selected students at the project school were identified as gifted using intelligence tests administered by the Counseling and Research Center and confirmed by the Science Committee of the Project Executive Board. There are two classes in each grade, consisting of 24 students in each class. Half of each class consists of gifted students, and the other half consists of undiagnosed students. The project school serves both the gifted and non-gifted and was founded in 2002 with the aim of achieving social, emotional and academic gains in both groups of learners (Davaslıgil & Leana, 2004, p. 96-97). In line with the purpose of this study, non-gifted students at the project school were excluded from both the treatment and control groups.
Academic achievement test. An academic achievement test was designed by the researcher to assess the participants’ deep and complex understanding of the 5th-grade science curriculum, specifically the unit “Exploring and Getting to Know the World of Living Things”. Forty-four items were developed on the basis of differentiated curriculum objectives and possessed the characteristics of both depth and complexity (see Appendix A). The items were submitted to five judges for review in terms of their scientific, psychometric and grammatical aspects. Flawed items were either corrected or replaced with new items.
In addition to the accuracy of the items, they were reviewed as to whether they served the purpose of the study. Three independent judges who were experts in science education were asked if the items were appropriate for evaluating the objectives of a differentiated curriculum developed on the basis of depth and complexity. They rated the items on a scale ranging from ‘highly disagree’ (1) to ‘highly agree’ (5). The average scores of the three judges were 4.77; 4.48; and 4.59 on a five-point scale. The average inter-judge reliability (Spearman Rho) coefficient was found to be .998. This high consensus among the judges also provided evidence of the content validity of the academic achievement test.
To evaluate the reliability and validity of the academic achievement test, 44 items were administered to 4th and 6th gifted graders in order to decide if questions are suitable for the 5th gifted graders. The administration of the achievement test to 4th and 6th grades had to be preferred by the author because of the limitation of time. The achievement test should be ready before the experimentally designed research was conducted and 5th grade gifted students were not taught the subject-matter while the test was being administrated. Besides this limitation, there is an advantage of this use in Turkey. In our country, Turkish educational system follows a spiral curriculum which means 4th and 6th graders were familiar with the concepts at varying degrees. Logically, 5th gifted graders’ understanding of those had to be somewhere between 4th and 6th gifted graders.
191 gifted 4th and 6th graders who enrolled in the Science and Art Centers after-school programs for the gifted in İstanbul, Ankara and Adana. In these centers, because there are fewer 6th graders than 4th graders, 79 gifted 4th graders in the initial sample had to be randomly eliminated. The results were 56 gifted 4th graders and 56 gifted 6th graders, whose characteristics were analyzed using a software program. According to the discrimination indices, 10 items that did not meet the criteria were discarded. The remaining items constituted the 34 items on the academic achievement test.
The Cronbach Alpha coefficient, a measure of reliability, was found to be 0.78. The evidence for criterion validity was obtained by calculating the correlation coefficients between the scores on the academic achievement test and the students’ fall semester grades in science education. The correlation coefficient for the 4th graders was found to be 0.14. The low relationship between the test scores and the grades of the 4th graders was expected because the 4th-grade students had not yet been taught the particular curriculum unit. In addition, their grades in science were generally high (average of 97.37; sd of 3.35). The correlation coefficient of 0.39 for the scores of the 6th graders on the academic achievement test can be considered satisfactory when taking into account the standard learning environment. As discussed earlier, in the introduction, these students are not necessarily offered a rich learning environment as a consequence of the attention placed on the needs of the average students. The 6th graders have been taught the subject matter in non-differentiated classrooms. This situation may explain the difficulty of the students experienced acquiring the content without differentiation.
Scientific process skills test. The Scientific Process Skills Test used in this study was originally developed by Burns, Okey, and Wise (1985) with the aim of measuring scientific process skills at the middle- and high-school levels. The 36 items in the Scientific Process Skills Test were translated into Turkish by Geban, Aşkar and Özkan (1992). Çakar (2008, p. 61) revised the test to improve its usability at the 5th-grade level by reducing the number of items from 36 to 24 with the help of three experts and a group of classroom teachers. The KR-20 reliability coefficient of the test was found to be 0.86. The average difficulty index was 0,58.
Scale of attitudes toward science education. The attitude scale used in this study was the Scale of Attitude toward Science and Technology Instruction developed by Nuhoğlu (2008). To evaluate the content validity, the items in this scale were revised by ten primary school teachers and six academicians at the department of primary school education. Three linguists checked the clarity of the language used in the scale. The three-point Likert scale was administered to 422 students in three primary schools in Üsküdar, İstanbul. The data were analyzed using the SPSS program. After performing the factor analysis, 10 of the 30 items were discarded. The resulting test included 10 negatively worded and 10 positively worded items. The Cronbach Alpha internal integrity coefficient was 0.87.
Copies of all the instruments are available from the authors on request.
ProcedureGroups. At the beginning of spring semester of the 2012-2013 academic year, 21 gifted 5th graders were administered the pre-tests of academic achievement, science process skills and attitude. After the pre-testing, students were assigned to two groups based on their (1) pretest scores, (2) fall-semester grades in science and (3) gender. The Mann Whitney U Test was used to check whether the two groups differed in terms of these variables. As shown in Table 2, there was no significant difference between the two groups at the level of 0.05. The groups were randomly designated the control group (n=10) and treatment group (n=11).
Table 2. Results of the Mann Whitney U Test Regarding the Grades and Pre Test Scores of the Treatment and Control Groups
Pre Tests
Groups
N
Mean Rank
Sum of Ranks
U
Z
Grades
Treatment
11
11.68
128.5
47.5
-.530
.590
AA
Treatment
11
11.05
121.5
54.5
-.035
.972
SPS
Treatment
11
9.64
106
40
-1.059
.289
ATSE
Treatment
11
11.27
124
52
-.212
.832
Differentiation. By modifying the general curriculum on the basis of depth and complexity, the differentiated and the general curriculum were made distinct from the standpoints of quality and level.
Quality of the content. Although the number of general curriculum objectives was reduced from 31 to 22, the meanings of general curriculum objectives were intensified by placing an emphasis on causality and were broadened by structuring a set of relationships. The differentiated content was organized around the theme of the system. This process established six categories of knowledge elements: ‘theme’, ‘principles’, ‘topics’, ‘big concepts’, ‘associations’, and ‘curriculum objectives’. These knowledge elements were hierarchically designed and interrelated. For example, under the theme of “system”, one of the differentiated curriculum objectives is “Students are able to explain the reason why vertebrae are a criterion used to classify animals by observing the features of vertebrates and invertebrates.” This curriculum objective has a connection with an association of “the similarities and differences”, which is related to the topic of “classes and species”. This topic is tied to a principle, namely that “A system consists of various components” (see Appendix B).
Quality in process skills. Turkish policy in the development of a national science curriculum generally meets the need of acquiring scientific process skills within various contexts and at different time intervals (Ministry of National Education [MoNE], 2005, p. 5). Aside from the National Science Educational Programs, additional scientific process skills are embedded to support a differentiated curriculum in terms of the constructs of depth and complexity: (a) to achieve a level of depth, students are guided to decide themselves by which strategy or method to develop explanations for facts, events and phenomena; and (b) to achieve a level of complexity, students are challenged to understand how scientific strategies and methods in the design, implementation and evaluation of scientific investigations are related to one another.
Level. Through modifications, the differentiated science curriculum was upgraded from a knowledge of classifications and categories at the understanding level to a knowledge of principles and generalizations at the analysis level (Anderson et al., 2001; see Appendix C). The sample activity shown in Table 3 provides insight into the differentiation of the science curriculum on the basis of depth and complexity: While students were forced to think about the core concept, they needed to pay attention to the range of possible explanations.
Table 3. An excerpt from the differentiated science and technology curriculum
Objective
Students will be able to explain why mushrooms are not classified as plants.
Preparation
A few empty frames are drawn on the board.
Arousal of attention
Students are asked to draw a picture of soil, a tree and a group of mushrooms within the frame. (While most of the students draw in their notebooks, a few volunteers can draw on the board.)
Reflection
Two pictures drawn on the board are referred to while asking students the question “Which one of the pictures reflects reality more accurately?”
Motivation
After taking a poll of the students, the correct answer is shared.
Challenge
By indicating the right picture, students are asked the question “How do you explain that mushrooms are in a different classification of living creatures, not animals and not plants, using this picture?” (Students are allowed to use their textbooks.)
Implementation. While the treatment group was offered the differentiated science curriculum by the researcher, the control group continued to be taught by their science teacher using the general science curriculum which is defined by National Ministry of Education. There is actually no extra core curriculum studies specific to gifted students in National Ministry of Education. See Appendix C for the comparisons between standardized science curriculum and the differentiated.
All the sessions in both groups were held in a classroom equipped with technological devices (a computer, a projector and a loudspeaker). Students’ science teacher was not informed about the experimental design. Daily instruction was provided in two 40-minute periods over a span of 4 weeks. After each group completed the program, the participants in the study were administered the academic achievement test, the Science Process Skills Test and the attitude scale as post tests. The administration of the tests spanned two class periods (2x40 min.).
Method of Analysis
The data obtained from the scores on the academic achievement test, the Science Process Skills Test and the attitude scale were analyzed with the aid of SPSS software, version 15. Nonparametric order statistics was used in compliance with the purpose of the study. The Mann Whitney U Test was performed to determine whether the mean results from the treatment and control groups differ significantly (Edwards, 1960, p. 417), and the Wilcoxon Signed Rank Test was used to compare the pre- and post-test samples (Hays, 1963, p. 635).
