۱۵ classes were in one of two groups: one group received graphic organizers at the beginning of a chapter; the other group did not receive graphic organizers. Each participating student in the study scored above the 60th percentile on a standardized achievement test. The treatment variable was the use of graphic organizers throughout the first seven chapters of instruction in the life science class. The control students did not have graphic organizers during the instruction of the first seven chapters. The same Life Science text was used in all 15 classes. Identical pre-tests and post-tests containing 50 items were used for evaluation purposes. Students in classes that used graphic organizers scored significantly higher on post-tests than students in the control group. The one-way analysis of covariance showed a statistically significant main effect (p .۰۰۱) in favor of the students who received instruction using graphic organizers. The conclusion drawn from this study was that the graphic organizer is an effective and practical teaching strategy. Hawk’s rationale was that graphic organizers provide an overview of material to be learned and a framework that in turn provides reference points to aid the learner in assimilating the new vocabulary and organizing the main concepts into a logical pattern.
Simmons (1988) specifically examined the differing effects of graphic organizers depending on whether the organizers were used before or after the presentation of the content and concluded that graphic organizers as advance activities were significantly beneficial on delayed assessments. Simmons (1988) compared the effectiveness of three instructional procedures for assisting sixth graders’ comprehension and retention of science content. The first instructional procedure included teacher-constructed graphic organizers before textbook reading; the second procedure utilized teacher-constructed graphic organizers after textbook reading; and the third procedure utilized a more traditional form of instruction consisting of text-oriented discussion and questioning before, during, and after textbook reading. Forty-nine students from three homogeneously grouped general science classes in a middle income suburban school participated in the study. Subjects in all groups participated in six consecutive 30 minute daily lessons on atomic structures and properties. Three measures, short term probes, immediate and delayed post-tests were administered to assess students’ comprehension and retention of science content. The probes were administered at the beginning of the third and fifth lesson and following the sixth lesson. The probes consisted of six short answer questions to assess students’ comprehension of recently studied content-area text. The immediate posttest comprised of twelve short answer items and was administered the day following the completion of the instructional sessions. This immediate post-test assessed the range of information taught during the six instructional sessions. A delayed post-test of similar format as the immediate post-test was administered eleven days after completion of the instructional interventions. The results of the study indicated that the placement or timing of the graphic organizer in the text reading was a significant factor in determining student performance on a delayed posttest. The use of the graphic organizer before text reading appeared to be more effective in the recall of text material, as measured by the delayed post-test. The results of the analysis of variance (ANOVA) indicated a significant main effect for treatment on this measure (p = .016). However, results from the immediate post-test produced no significant differences in performance among the three instructional procedures.
Horton, Lovitt, and Bergerud (1990) investigated the effectiveness of graphic organizers for students with learning disabilities low achieving remedial students, and students in regular education. The study also investigated the effects of different forms of instruction utilizing graphic organizers. The study compared teacher directed graphic organizer instruction, student directed instruction with text reference, and student directed instruction with clues to student self study of content material. Three classes of middle school science, three classes of middle school social studies and three classes of high school social studies participated in the study. In each subject area, two classes were randomly selected to serve as experimental groups and a third class served as a “neutral group”. The experimental classes included eight students with learning disabilities. The nine students identified as “remedial” were all in the same high school social studies class. The graphic organizers in the study were hierarchical in format. The outcome measures were the content of the students’ versions of the graphic organizers compared to a criterion organizer. Within a subject area, two passages were selected from the same chapter of text. The neutral group read one passage and independently completed the corresponding organizer, followed immediately by reading the second passage and completing the accompanying student graphic organizer. According to the authors, the purpose of the neutral classes was to evaluate the difficulty of the two reading passages. The most difficult passage was assigned the graphic organizer treatments while the easiest passage was assigned a self-study condition. The results of three separate experiments indicated that teacher directed, student directed with text references, and student directed with clues produced significantly higher performance than self-study for students with learning disabilities, remedial students, and students in regular education (p .۰۱).
Armbruster, Anderson, and Meyer (1991) examined the effectiveness of graphic organizers on fourth and fifth grade students’ ability to learn from reading their social studies textbooks during the course of an entire school year. The study involved four replications or rounds, in which instruction that used frames to supplement the textbook was compared with instruction provided by the teacher’s edition of the textbook. A total of 365 children from ten elementary schools participated in the study. There were two types of frames used in the study. One type of frame depicted a sequence with arrows connecting a series of boxes; the second depicted a matrix comparing characteristics and examples of concepts. In the first round of the study, there were three experimental conditions: a student framing condition in which students completed the frames independently, a teacher led framing condition, and a control condition using textbook resources. Each teacher was assigned to all conditions. In the subsequent rounds of the study, the student framing condition was conducted in groups instead of each student working independently. In each round, students in the framing conditions scored significantly higher on recognition and recall tests than did students in the control group. However, scores when students completed the frame, both independent and group completion, did not differ significantly from the scores when teachers assisted in completing the frames. The researchers concluded that frames help readers with selecting and organizing information from the text.
In one test of validity; Markham, Mintzes, and Jones (1994); a sample of college students were used to compare concept mapping scores with scores obtained on a card sorting task of key terms. The results indicated that the concept maps of biology majors in comparison with non-majors included more branching and more hierarchies, indicating greater concept differentiation. The cross links, indicative of conceptual integration, and examples in maps of the biology majors far surpassed those of non-majors. Comparable results were found with the card sorting assessment that establishing the concurrent validity of the concept mapping. When constructing the maps, students were given a list of key terms and concept
s and told to construct a concept map using those terms.
Zaid (1995) applied the semantic mapping technique in teaching reading to his students at Abha college of Education. He explained that semantic mapping has been shown to be a beneficial learning/teaching technique for native speakers of English at all grade levels in regular and remedial classrooms as well as for those who are learning-disabled. He added that students who use semantic mapping manifest considerable improvement in reading comprehension, written expression, and vocabulary development. He suggested some areas of correlation between what a semantic mapping activity does and the principles and objectives of communicative language teaching (CLT). For the students, the map was providing a graphic conceptualization of their randomly given ideas. There are three places in a lesson where semantic mapping may be used as he clarified:
۱- As a pre-assignment strategy to activate students’ prior knowledge or to help the teacher in assessing the students’ readiness to do the assignment.
۲- As a strategy to allow students to record what they are learning during the assignment.
۳- As a post-assignment strategy to allow them to integrate or synthesize what they have studied. He concluded that semantic mapping is interactive, it allows for sequential negotiation. It is an information-gap activity since students must fill in gaps in the map and in their personal schemata of the topic as the map takes shape. Moreover, it is a predictive activity .It is student centered because the semantic map makes use of the students’ prior knowledge and because students control the input at each stage of the map’s building. It is teacher-friendly because it allows the EFL teacher unobtrusively to pre-assess the students’ readiness to do an assignment, take immediate steps to enhance their preparation and to post-evaluate how well the students integrated or synthesized what they had studied. Finally, it is an integrative activity, since it allows students to connect previous knowledge with new knowledge, thereby expanding their reservoir of knowledge through that interrelationship. He recommended that there should be inclusion of semantic mapping activities in the technical repertoire of CLT.
Doyle (1999) examined the effectiveness of student constructed graphic organizers versus teacher directed note-taking. The subjects in this study were eight high school students with learning disabilities and were conducted in a Resource United History II class. The study used two interventions for teaching information from the textbook. The first intervention entailed presenting different graphic organizers to students and having them fill in the graphic organizers. In the second intervention, the teacher presented the information through lecture and had the students copy notes that were written on the board. On completion of each of the chapters of text presented through the two interventions, the students participating in the study took a chapter textbook test. Students received higher scores on post instruction tests when graphic organizers were used compared to when the more traditional lecture

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