Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 The Development of Geometri Teaching Materials Based on he Students’ Mathemat Constructivism to Improve t ic Reasoning Ability through Cooperative Learing Jigsaw at the Class VIII of SMP Negeri 3 Padangsidimpuan Izwita Dewi Muhammad Syahri Harahap Department of Mathematics, Science Faculty, State University of Medan, Jl. Willem Iskandar Pasar V Medan Estate, Zip Code 20221, Indonesia Abstract The purposes of this research were to know the validity, practicality, and effectivity of geometrical learning material based on the constructivism to Increase students' mathematic reasoning ability and increasing students'mathematic reasoning ability by using learning material at the grade VIII of SMP Negeri 3 Padangsidimpuan. Type of the research was the development of research by using modification of the 4-D development models. The steps of this research were the defining step, designing step, developing step, and dissaminating step. The experiment was done at the grade VIII students of SMP Negeri 3 Padangsidimpuan. Result of the research Showed that: 1) The validity of geometrical learning material based on the constructivism to Increase students' mathematic reasoning ability at the grade VIII of SMP Negeri 3 Padangsidimpuan was very valid, 2) practicality of geometrical learning material based on the constructivism to Increase students 'mathematic reasoning abilityat the grade VIII of SMP Negeri 3 Padangsidimpuan was practical to be used, 3) geometrical learning material based on the constructivism to Increase students' mathematic reasoning ability at the grade VIII of SMP Negeri 3 Padangsidimpuan was effective, and 4 ) increasing of students' mathematic reasoning ability by using geometrical learning material based on the constructivism at the grade VIII of SMP Negeri 3 Padangsidimpuan was on the medium category. Keywords: Development, Geometrical Learning Materials based on the Constructivism, Mathematic Reasoning 1. Introduction Along with the development of science and technology, people are required to have the ability to think critically, systematic, logical, creative thinking, and cooperate effectively so that they can be developed forward in this globalization era. Formal education in this regard has an important role in the development of the things which had been mentioned above, namely by making quality learning. One of the most influential in the learning is appropriate teaching materials. Teaching materials that can accommodate the diversity of students' ability with their characteristics and make them become active that’s a must at this time. Wijaya and Rohmadi (2009: 239) states the success of a teaching-learning process is not solely determined by reliable teacher, good input, and teaching facilities such as school buildings, teaching tools, libraries, and so were adequate, but the election of appropriate and quality teaching materials also have a dominant role. The cause of the difficulties students in understanding mathematical concepts after analized is the less of effective material, so it is needed the effective material. Teaching material is one of learning tools that can help students in learning. (Pangesti, 2012: 2) argues that the teaching material is the foundation of learning in the classroom. This opinion can be interpreted that the teaching materials are fundamental in the learning process, so important these materials it needs attention in its design. The success of the mathematic learning purpose is very influenced by teaching materials used. As found by Ramdani (2012: 50), which focuses on developing teaching materials directed to improve thinking skills high level math students, such as communication skills, reasoning, and connections mathematical problem solving is not routine, prove or submit justification, as well as discover patterns and propose general form well. Learning math exacts standards of mathematical process can be cultivated by making teaching materials that support the standard process capabilities. National Council of Teachers of Mathematics (NCTM, 2000), stated that the 5 skills necessary process of the students, namely: (1) problem solving; (2) reasoning and proof; (3) communication; (4) connection; and (5) representation. Those skills are the a high order mathematical thinking that is important to be developed by students in the learning process of mathematics. Reasoning ability is something that must continue to evolve and have different stages in life on each individual and it is important in knowledge. Tan (2007) in (Koray, 2013: 2746) Reasoning ability has an important role in construction of science meaningfully concepts.Depdiknas (in Sadiq, 2004: 3) states that "mathematical material and mathematical reasoning are the two things that can not be separated, ie, mathematical material is understood through reasoning and reasoning can be understood and trained through learning math ". Reasoning aspect is the ability which has been had by the learners as a standard which enables a person can master the concept generally and specifically in depth. 68 Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 Mathematical reasoning skills students in Indonesia, can be seen from the results of research conducted by The International Trends In Mathematics and Science Study (TIMSS) in Sanjaya (2006: 4), coordinated by the International Association for the Evaluation of Educational Achievement (IEA). The results of the TIMSS in 2011 showed Indonesia was ranked 38 out of 45 countries with an average score of 386, it means it is stiil low level. The questions which are developed by TIMSS include four cognitive domains namely knowledge of the facts and procedures, application of the concept, a routine problem solving and reasoning. Based on the previous exposure, so the development of teaching materials and improving reasoning skills should be an attention focus in mathematics learning, because by trying to develop appropriate teaching materials such as books and worksheets which are accompanied by supporting lesson plans will push to develop the skills of mathematical processes. Context's ability in this regard emphasized the reasoning. At this time, learning is emphasized on student-centered learning where students are given the opportunity to make sense of the problems which is faced until he obtained a settlement or the appropriate conclusions. Remembering the demands of an active learners, reasoning and teaching are just enough as facilitator then one suitable approach is constructivism. Constructivism assumes that learning is an active process where learners using all five senses to construct their understanding. Constructivism also can improve reasoning. The constructive nature of students' learning processes, have important implications for teachers who wish to model of scientific reasoning in an effective fashion for their students (Cakir, 2008; 193). It was clearly said that constructivism learning is one of the solutions for scientific reasoning which is appropriate with the learners. Constructivism assumes that knowledge cannot be granted. Knowledge can only be offered to students, the rest depends on the efforts of students to construct knowledge in order to get a good learning outcomes. That is if it is related Yerizon’s research, et al with the use of geometry-based Instructional Materials Constructivism applied effectively used as teaching materials and to improve learning outcomes (Yerizon, et al, 2012; 56-57), so that the combination of teaching materials and the theory of constructivism is one of the good breakthrough. The results of the survey researchers (dated 22 September 2015 for the provision of diagnostic tests to students of SMP Negeri 3 Padangsidimpuan showed that 70% of the total number of students face the difficulty in solving problems in the form of reasoning geometry measurement of mathematics. Remembering one of the subjects that are important in school is geometry. Geometry by Kartono (2012: 25) "based on the point of view of psychology, geometric abstraction was the presentation of visual and spatial experience, eg field, pattern, measurement and mapping". Diagnostic tests performed showed that students feel the difficulty in resolving questions that test reasoning ability analogy. As many as 70% of students are not able to resolve the questions reasoning analogy. This case requires us as a teacher to improve reasoning and select appropriate learning strategies to the material in order to reduce that errors. Anticipating these circumstances, the strategies which is done need to be reformed. Tasks and role of the teacher are no longer as informants but as a driver of student learning in order to construct their own knowledge, in addition to approaches, teaching staff are also required to have teaching materials learning is the handle in carrying out teaching and learning activities in the appropriate grade student characteristics. Based on the observations and informal interviews were conducted to the teachers and students of SMP Negeri 3 Padangsidimpuan on September 22, 2015. The results that can be seen was instructional materials which is used had not been effectively to sharpen students' reasoning. More specifically, because of the lack of teaching materials such as books, LKS (Student Worksheet) that support reasoning ability also affecting patterns of RPP (lesson plan) is very conventional and impressed it is just. Further observation, books and worksheets that are used during the time in SMP Negeri 3 Padangsidimpuan only in the form of books and worksheets with questions about the routine without a method to enable the student activity prior to the material geometry depends on teaching materials in addition, RPP (lesson plan) which is used also less in accordance with the character of the students which are very diverse with conventional methods that have been there from many years ago without any renewal. The limitations which are exist for a long time cause students rely on notes from the teacher and always rely on the teacher's explanations, no effort / desire to find their own solutions. Here's a picture worksheets and lesson plans used in the school: 69 Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 Figure 1. Example of worksheets and lesson plans used in SMP N 3 Padangsidimpuan According to a series of interviews and direct observation dated September 22, 2015, clearly described how the necessary a creation of a teaching material that is based on constructivism. The other combination except teaching materials based on constructivism is a learning strategy. Applying cooperative learning in the classroom based on several studies, which have found that when students work together to achieve a group goal, making them express good norm in doing whatever which is necessary for the success of the group. Jigsaw type of cooperative learning can enhance students' learning activities. As Menduo and Xialing (2010: 114) argue that "Jigsaw is said to be Able increase of student's learning since a) it is less threatening for many students, b) it increases the amount of student participation in the classroom, c) it reduce the need for competetiveness and d) reduce it's the teacher's dominance in the classroom ". Consequently, jigsaw strategy can successfully reduce students' reluctance to Participate in the classroom activities and help create learner-centered active in atmospher. Jigsaw is said as the learning which can improve students' learning activities because a) reduce the penalty for students, b) increase the participation of students in the classroom, c) reduce the necessary to compete d) reduce the dominance of the teacher in the classroom as the effect, learning strategies jigsaw can reduce the reluctance of students to participate in the classroom activities and help create student-centered liveliness. Based on the explanation above, the question of this study are as follows: (1) How is the validity of the development of teaching materials based constructivism geometry to improve students' mathematical reasoning through Jigsaw cooperative learning in class VIII of SMP Negeri 3 Padangsidimpuan? (2) How is the practicality of teaching materials based constructivism geometry to improve students' mathematical reasoning abilities through Jigsaw cooperative learning in class VIII of SMP Negeri 3 Padangsidimpuan? (3) How is the effectiveness of teaching materials based Geometric Constructivism to improve students' mathematical reasoning abilities through Jigsaw cooperative learning in class VIII of SMP Negeri 3 Padangsidimpuan? (4) How is the increasing ability of mathematical reasoning class VIII of SMP Negeri 3 Padangsidimpuan using Geometry teaching materials based constructivism through cooperative learning of Jigsaw? 2. Theoretical Description 2.1 Ability of Mathematical Reasoning Reasoning ability is the ability of students to think logically according to specific workflow framework. Reasoning is an ability that must be owned by the students when doing the math learning process. This reasoning abilities is also as one of five standard mathematical learning process that has been set. The fifth standard process that is problem solving, reasoning, communication, representation and the connection). (NCTM, 2000) Reasoning is a thinking process to take a conclusion from the information obtained. Bruner (Lohman, 2009: 3) states that the reasoning Refers to the process of drawing Conclusions or inferences from information. Reasoning always requires going beyond the information that is given (Bruner, 1957). Reasoning as the outline has two types, namely inductive reasoning and deductive reasoning which is also called as deduction. Sumarwo (2007: 116) explains that "Equality between deduction and induction is that both arguments have a structure consisting of several premises and a conclusion. The difference between deduction and induction on the basis of inferences and conclusions properties which are lowered." Bani (2011: 13) reveals, Inductive reasoning is a thought process that attempted to link facts or special events which had been known strives to the conclusion of a general nature. Deductive reasoning is a thought process to draw conclusions about specific things that rested on a common things or things that have previously been 70 Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 demonstrated (assumed) the truth. A. Inductive Reasoning Based on the Bani’s opinion above, it can be concluded that inductive reasoning is drawing conclusion based on the number cases or limited example. It explains that the reasoning is reasoning which is continue from the specific things to the general things (generalization). It means that the thinking activity draw a conclusion or making a new statement of a general based on the facts that are specific which had been known well. Learning begins by giving examples or specific case towards a general concept. Inductive reasoning is divided into two, namely: 1) Generalization (Rahman, 2014.38) Generalization is a process of reasoning which is based on the examination of things to taste and then get the conclusion for all or most of these things, for an advanced level mathematics, to verify the correctness of results which is gotten in a conlusion, so it is done examination in mathematical induction. It is intended to prove whether the inference obtained apply to all. This means in generalization doing observations of specific examples and then be able to find patterns or rules from these examples that are generally. 2) Analogy Analogy is the reasoning of a certain thing to another similar one thing and then conclude it. The conclusions which is gotten from the analogy way, that the conclusion of a special opinion of some special opinion of others, by comparing the situation or pattern of the previous one. This is in accordance with the opinion of Rahman (2014: 38), "The analogy is the reasoning of a certain thing to another similar thing then conclude what is right for one thing will also be true for other things". B. Deductive Reasoning Based on the opinion of Bani and Sumarmo which have been disclosed previously, it can be concluded that deductive reasoning is reasoning that goes from things that are common (generalization) to things that are special. This deductive reasoning must be a previous statement which was assumed to be true, so that produce a new statement which is referrenced to the statement that had been assumed to be true before. Making a deductive proof process will involve theory and other mathematical formulas which have previously been substantiated the truth as deductively also. There are two types of deductive reasoning, namely: 1) Syllogism Deductive reasoning is often used is the syllogism. Syllogism is reasoning indirectly. In the syllogism there are two premises and a conclusion premise. The second premise is the premise of the general / specialized major premise and the premise / minor premise. From both of those premises, the conclusion is formulated. 2) Conditional Conditional Reasoning is a part of the thinking that is changing the information which had been provided to get a conclusion. The existing problems in the conditional explain the relationship between the two conditions or circumstances, which are expressed by the relationship if ..... then ...... Reasoning conditionally divided into two, namely: a) Ponens Modus Ponens Modus is the relationship between premises. The first premise is a conditional statement that is using "If ... (is antesenden), then ... (is the conclusion)". The second premise is not conditional statement. There are two types of ponens modus reasoning, they are strengthening antesenden (component P) and strengthening consequent / conclusion (q component). b) Tollens Modus There are two types of reasoning, they are denying antesenden and consequently denying consequent. Denying antesenden means if the second premise denies the right antesenden on the first premise. Based on the understanding of some experts and the explanations above, it can be concluded that the ability of reasoning is a thinking activity to make a new statement or conclusion which are referrenced to the previous statements which are assumed to be true. Reasoning indicators are gotten on the basis of the conclusions which are gotten after making the observation, looking for the truth of revelation, and find patterns to make generalizations. Mathematical reasoning is the ability to think for obtaining a logical conclusion based on the facts and the relevant sources. The conclusion which is gotten based on the previous statement that is assumed to be true. Researchers set, the indicators which are used in this study are 4 indicators which are perceived appropriate with the characteristics of students and some clarification on aspects of the reasoning which had been explained above. Indicators reasoning skills of students as follows: 1. Can determine the similarity relationship in a pattern of nature 2. Can draw general conclusions 3. Can make the conclusion of an argument by using the principle of modus ponens 71 Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 4.Can make the conclusion of an argument by using the principles of syllogism 2.2 Theory of Constructivism Based on constructivism view, knowledge is a construction (formation) of people who know something (schemata). Knowledge can not be transferred from the teacher to the others, because each person has their own schemata about what he knows. The most basic constructivism is form piagnet and Vygotsky. In this case the understanding as the reference is Vygotsky's theory. Vygotsky in (Cahyono, 2010: 443) states that learners in constructing a concept needs to pay attention to the social environment. This Constructivism by Vygotsky (Cahyono, 2010: 443) called socio-constructivism. There are two important concepts in Vygotsky's theory, namely the Zone of Proximal Development (ZPD) and scaffolding. Zone of Proximal Development (ZPD) is the distance between the actual developmental level which is defined as the ability of problem solving independently and the level of potential development is defined as the ability of problem solving under the guidance of adult or in collaboration with more capable peers. Scaffolding is giving some assistance to students during the early stages of learning, then reduce aid and provide an opportunity to take over greater responsibility after he can do it. Scaffolding is the assistance provided for learners to learn and solve problems. The assistance can be in the form of guidance, encouragement, warning, describe the problem in solving steps, provide examples, and other measures that allow learners to learn independently. Formation of knowledge is a cognitive process which occurs assimilation in order to achieve a balance so that formed a new schemata. Constructivism assumes that knowledge can not simply be transferred to the student. Knowledge can only be offered to students, the rest depends on the efforts of students to construct knowledge. (Gabert, 2011: 37) Constructivism emphasises the importance of the knowledge, beliefs and skills that an individual brings to the experience of learning. In its many different forms (from a Piagetian notion of an individual's adaptation and assimilation of new information to an emphasis on learning as the product of complex socio-cultural processes, as suggested by Bruner, Lave, Rogoff, and Vygotsky), the learner is an active participant. Based on the experts’ suggestion that learning is an active process of the subject learn to construct meaning something, whether it is text, dialogue, physical experience and others, so that learning is a process assimilate and relate experiences or material which are learned with the understanding which they have, so understanding will be developed. A teacher’s constructivist class does not teach students how to get results, but present the problem and encourage students to find their own way to solve the problems. Teachers try to not say that the answer is correct or not correct when the student gives an answer, but teachers encourage students to agree or disagree to the idea of a person. Exchanging of ideas until agreement was reached on what can be a reasonable student. Students are empowered by the knowledge that resides within them and the environment. In line with the statement of Thompson (2013: 1) There are two principle schools of thought within constructivism: radical constructivism (some people say individual or psychological), and social constructivism. Based on constructivism understand Vygotsky. The principles that are often taken out of constructivism according Trianto (2013: 75), among others: a) The knowledge built by students actively b) The pressure in the process of learning lies in students c) The teaching is to help students learn d) The pressure in the process of learning more on the process rather than the final result e) The curriculum emphasizes student participation f) Teacher as facilitator (giver scafholding) 2.2.1. Geometry-Based Instructional Materials Constructivism Teaching materials is prepared by using a constructivism approach, where students build / find themselves how geometry concepts. With there are questions which are given require students to work and experience by themselves the knowledge. Finally, the students understand the learning materials which are provided and acquiring new knowledge. Constructivism based teaching material (Adina, 2012: 24) contains the following elements: 1) Orientation, it means that teaching materials provide opportunities for students to develop motivation in researching a topic. Students are given the opportunity to conduct observations of the topics to be studied. 2) Elicitation, it means that using teaching materials help students express ideas clearly by discussing, writing, creating posters, and others. Students are given the opportunity to discuss what will be obesrved, in the form of text, images, or posters. 3) Restructuring of ideas, in this case there are three things. a) Clarification of ideas which are contrasted with the ideas of other people or friends through discussion or through the collection of ideas. Faced with other ideas, someone could be 72 Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 stimulated to reconstruct the ideas that did not fit or otherwise, become more confident if his ideas is suitable. b) Build a new idea is happened if in the discussion his idea is contrary to another idea or his ideas cannot answer the questions which is given by the friends. c) Evaluate new ideas with experiments, if it is possible, it is better if the new idea is formed to be tested with an experiment or a new issue ones. 4) The use of the idea in many situations. The idea or knowledge that have been formed by the students need to be applied in a variety of situations encountered. This will create a more complete knowledge of students and even more detailed with all sorts of exceptions. 5) Review, how the idea was changed, may occur in the application of knowledge to the situation faced every day, someone needs to revise his ideas either to supplement it with an explanation or perhaps turn it into a more complete. 2.3 Cooperative Learning Jigsaw Cooperative learning model is one model of learning that supports contextual learning. Jigsaw type of cooperative learning is a type of cooperative learning that consists of several members in one group responsible for mastering parts of the material and able to teach the material to other members in the group (Arends, 1997). Khanafiah (2010: 54) argues in a jigsaw type of learning, students are divided into groups whose members heterogeneous. Each is responsible for studying the assigned topic and teach the group members, so that they can interact and help each other. This means cooperative learning jigsaw model is a cooperative learning model in a way students learn in small groups of four to six people are heterogeneous and students work together in positive interdependence and responsible independently. The mechanism of this technique, students can work together with other students and have more responsibility and also have many opportunities to process information which is gotten and improve the skills to communicate and socialize. The learning model like this should be optimized because it can improve the ability to create on the students and certainly improve student achievement. Cooperative learning jigsaw can be implemented by following the steps as suggested by RJ (2012: 271), namely: i. Students are grouped into four member team ii. Each person in the team is given a different part of the material iii. Each person in the team is given a part of the material assigned iv. Members from different teams who have studied the same sections / subsections meet in the new group (group of experts) to discuss their section v. After finishing discussions with a team of experts, each member returns to the original group and take turns teaching their teammates about their master section and any other member listened sincerely vi. Each team of experts presented the results of discussions vii. Teacher gives evaluation viii. Closing Figure 2.1 Schematic Model Cooperative Learning Jigsaw (Pujianto: 2015) Figure 2.1 Schematic Model Cooperative Learning Jigsaw (Pujianto: 2015) 73 Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 3. Research Methods This research includes depelopment research using 4-D model of development Thiagarajan, Semmel, and Semmel (1974). 3.1 Subject and Object Subjects in this study were students of class VIII of SMP Negeri 3 Padangsidimpuan 2015/2016 academic year, whereas the object of this research is Geometric Constructivism Teaching Material based on limas and prism material and mathematical reasoning abilities of students. A test I is done in class VIII / 2 and II trials is done in class VIII / 1. 3.2 Development Procedure Learning Tool Learning toolswhich are developed: the implementation of the Lesson Plan (RPP), Student Books, Teacher Books, Student Worksheet (LAS) and the Learning Ability Test, especially mathematical reasoning skills students. Learning model of learning tools use the 4-D model. But, this stages was not done, so that it was not explained in depth. The development model of this research is described in Figure 1 below. Figure 3 : Chart Development of Learning Devices 4-D Model (Modified Yuliani & Saragih, 2015:119) 74 Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 3. 3. Instruments and Data Analysis Techniques Instruments and tools for collecting data in this study are test, questionnaire and observation sheet. For more details can be seen in Table 1 below. Table 1. Instruments and Techniques for Collecting Data Aspect assessed Instruments Data observed Respondents Validity of learning implementation plan, student’s validity of Validity sheet book, teacher’s book, worksheet, mathematical Expert Teaching material reasoning ability test Practically of learning implementation plan, Practically of Validity sheet student’s book, teacher’s book, worksheet, Expert Teaching material mathematical reasoning ability test Quistionnaire Student’s response Subject test Effectiveness of Test Mathematical reasoning ability test Subject test Teaching material Observation sheet Student activity Observer Enhancement of (Pretest and Posttest of mathematical reasoning Test Subject test reasoning ability ability) 3.3.1. Validity Analysis of Geometri Teaching Materials Based Constructivism Development of Teaching Materials are validated by five validator. The criteria for the validity of Subjects as follows: Table 2. Validitas Category Level No Va or average value Criterion validity 1 1 ≤ Va < 2 Invalid 2 2 ≤ Va < 3 less valid 3 3 ≤ Va < 4 enough Valid 4 4 ≤ Va < 5 Valid 5 Va very Valid Source: (Sinaga, 2007:161) Note: Va is the value of determination level validity Subjects Geometry based Constructivism. The criteria stated teaching materials have a good degree of validity, if the validity of the minimum level reached is valid (4 ≤ Va <5). Teaching materials have been revised based on input from experts and samples tested outside of the classroom in order to get eligible Subjects. Then, the test results are analyzed for validity and reliability. The formula used to calculate the validity is the product moment correlation (Arikunto, 2012: 87), that is: Note: X : score items Y : total score r : correlation coefficient between the item score and total score xy N : the number of students who take the test (sample) Then, to determine the coefficient of reliability of a test used in narrative form alpha formula (Arikunto, 2012: 122) as follows: Note: : reliability coefficient test n : the number of test items : the number of variance test scores of each item. : total variance 3.3.2 Practical Analysis of Geometri Teaching Materials Based Constructivism Geometry Teaching Materials based constructivism to improve reasoning ability to be practical if it fills indicators : 1) Validator stated that geometri teaching materials based constructivism can be used with little revision or not. How to provide practicality on teaching materials have been created by giving a questionnaire about 75 Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 the assessment of teaching materials to validator with validation sheets of geometry teaching materials based constructivism. The evaluation criteria for instructional materials are: A : Can be used without revision B : Can be used with little revision C : Can be used with many revisions D : Not usable 2) positive response of students indicated from questionnaire. Analysis of the answers questionnaire responses of students to the teaching material is used as a reference that students are able to use teaching materials. To analyze the data are responding students use the formula: Note: RS : The percentage of students with specific criteria f : Total Score n : maximum score Determine the average score of the positive response of students, and then determine which categories of response or the response of students to a criterion by matching the results with the percentage of positive criteria, according Khabibah (Yamasari, 2010), that is: 85% ≤ RS : very good 70% ≤ RS < 85% : good 50% ≤ RS < 70% : less good RS < 50% : not good Geometry teaching materials based Constructivism to improve the reasoning ability to be practical when respond of students is well on teaching materials. 3.3.3. Effectiveness Analysis Geometry Teaching Materials Based Constructivism Geometry teaching materials based constructivism is said to be effective if it fills indicators : a. Geometry teaching materials based constructivism to improve mathematical reasoning abilities are effective if ≥ 80% of all test fill mastery learning (Yamasari, 2010). b. The activities of the students indicated positive of the observation sheet. To analyze the scores given by the observer by using the formula: note: AS : Percentage of Student Activities f : Total Score n : maximum score Determine an average score of student activity then matches the results with the percentage of positive criteria, according Khabibah (Yamasari, 2010), that is: 85% ≤ AS : very positive 70% ≤AS< 85% : Positive 50% ≤AS< 70% : less Positive AS< 50% : not Positive 3.3.4. Analysis enhancement of mathematical reasoning ability Enhancement of mathematical reasoning ability students after using teaching materials calculated by using N- gain. calculating N-gain formula is used: N- gain index criteria are : g > 0,7 : High 0,3 < g : Medium g 0,3 : Low (Hake, 1999) 4. Results The results of the development Geometry teaching materials based constructivism are presented as follows : 4.1 Define Geometry teaching materials based constructivism to improve reasoning ability is designed based on fond-end 76 Journal of Education and Practice www.iiste.org ISSN 2222-1735 (Paper) ISSN 2222-288X (Online) Vol.7, No.29, 2016 analysis start from interview with teachers, analyze mathematic syllabus, analyze and meriview reference books that can be used to teach the subjects of mathematics, as well as studying the characteristics of the students. 4.2 Design This stage, designed learning implementation plan (RPP), books and worksheets for geometry material based constructivism and cooperative learning jigsaw as well as designing the assessment that leads to mathematical reasoning abilities of students. a. Learning Implementation Plan. Learning implementation plan arranged for 4 meetings each contains 1. Identification of subjects, standards of competence, basic competence, indicators, learning objectives, teaching materials, fittings, learning model, learning scenarios and assessment of learning outcomes. The material at the first meeting determine the formula is the surface area of the cube, at the second meeting of determining the surface area of the beam, at the third meeting of determining the volume of a cube, and the fourth meeting of determining the volume of the beam. Learning implementation plan is designed using the syntax cooperative learning jigsaw. b. Book Based on the analysis front-end, designed a geometry teaching materials based constructivism to improve mathematical reasoning skills students according to student characteristics. The book contains material developed extensive geometry and volume as well as problems to be solved by the students in groups and independently. Teaching materials in the book using the concept of questions and explanations that support the process of constructivism. Geometry Teaching materials based constructivism focused on improving students' mathematical reasoning abilities. b. Student Worksheet Student worksheet arranged for containing four meetings about, the cube surface area, surface area beam, cube volume and the volume of the beam. Student worksheet is designed for cooperative learning Jigsaw. c. Mathematical reasoning ability test. Preparation of the test the ability of reasoning based on indicators. Tests are arranged in the form description. This test uses the reference benchmark assessment (PAP), because this test is used to measure how far the indicators that have been formulated and attempted to rise. Shaped mathematical reasoning ability test description consists of four items. The time allotted to complete all of these questions is 80 minutes. 4.3 Develop a. Validation validation of implementation plan, books, worksheets and reasoning ability tests conducted by experts and practitioners. Validation of experts made to the equipment and instruments developed to produce devices and instruments eligible. The expert in question in this case is the validator competent covering Lecturer Mathematics Education courses Unimed, teacher in SMP Negeri 3 Padangsidimpuan and teacher in Ponpes Nurul Palah South Tapanuli. Based on the results of expert assessment then made revisions to devices and instruments. Advice from validator is used for the improvement of devices and instruments. Following the assessment of validators: No Devices is rated Average Criterion validation Result 1 Learning Implementation Plan 89,07 very valid 2 Book 89,07 very valid 3 Student worksheet 90,25 very valid 4 Mathematical Reasoning Ability Test Little Revision and not Based on the validation results of learning implementation plan, books, worksheets and tests of mathematical reasoning skills obtained information that all validators say that the device developed valid. Questions about the validity of research geometry teaching materials based constructivism to improve mathematical reasoning has been answered. b. Trial of Teaching Material Teaching material were tested in field trials stage a revised teaching materials based on the comments given students in the testing phase. Books revised expected to be effective for use in learning.. a. Practically Test The first criterion, from experts / validators and practitioners (teachers) is based on responses of experts / validators and practitioners (teachers) states that geometry teaching material based constructivism has to be used with a little revised so that, in summary criteria of practicality first been filled which can be used with little revision. The second criterion is on the analysis of answers to questionnaire responses of students to teaching materials response analysis results of students to teaching materials. Based on calculations score obtained: RS = 81.58%. 77