HOW THE GENERATIF LEARNING BASED HANDS ON ACTIVITY TO INCREASE THE CRITICAL THINKING SKILL?

Physics has being the most difficult subjects for students, because physics is always associated with mathematics. Studying about physics is not merely know the math, but students are expected to understand the concepts contained in it, write it into the physical symbols, understand the problem and know how to solve them. However, most students have not been able to resolve the problems of physics given by the teacher and not able to respond to what is presented by the teacher. For example, when the teacher provides questions to the students about a concept, students tend to be silent and not able to answer that question. Students having difficulty stimulates memory to remember knowledge gained previously. And when the students put forward ideas, not shown smoothness respond to problems and materials.

Physical education can be interpreted as a form of learning to understand the nature and use of science that has been studied in relation to individual behavior.Physics itself can teach someone to get some physical skills such as being scientific skills and thinking skills. Physics education is also expected to create educational success in delivering community life for more advanced and competitive. These expectations are contained in the national education goals which according to Law No. 20 of 2003 on the national education system, education is a conscious and deliberate effort to create an atmosphere of learning and the learning process so that learners are actively developing the potential for him to have the spiritual power of religion, self-control, personality, intelligence, character, and skills required him , community, nation and state. One of the goals of learning physics is to develop the ability to reason in thinking inductive and deductive analysis using the concepts and principles of physics to explain natural events and resolve problems both qualitatively and quantitatively.

To achieve the objectives above various efforts have been made ​​by the government in order to optimize student learning outcomes. One of the government's efforts that have been implemented are the enforcement Unit Level Curriculum (SBC). Students study physics not only learn information about the concepts, facts and the law in the form of a statement of knowledge but also learn about how to acquire the knowledge, means and applied physics at work in the form of procedural knowledge including work habits scientific method and scientific attitude. Not only is it the government has now prepared and is implementing a national curriculum in 2013 with the hope of improving students' thinking skills in order to build student character and emotional students. One part of the thinking ability is the ability to think critically. Critical thinking is one of the many important skills in thinking that must be possessed by students because critical thinking will make a person prone to proceed and use the information to find the solution of a problem. Critical thinking dispose that influence the success not only in teaching, learning and other things, but also control ourselves and approach with others (Kawashima, et.al, 2007: 188). Therefore, the ability to think critically is one of the basic capital or intellectual capital is very important for everyone.

In relation to the ability to think in particular the critical thinking skills of government has been to integrate learning across the curriculum in 2013 with a scientific approach and some learning models. And at the same time cooperate with educational researchers in developing learning models that can be applied to a wide variety of subjects.

The efforts undertaken by the government is good, but in fact the government's efforts have not been sufficient and able to optimize students' critical thinking skills.Various learning models that have been used in study of physics is also not optimally in optimizing students' critical thinking skills. This is due in particular teachers in physics most are still implementing the learning tends to be behaviorism, which is concerned with the transfer of knowledge by teachers against students who are not in line with the lesson plan. So that students are not able to receive the material as a whole and learning physics was less marked, so it can not cultivate the ability to think, move / work and behave and communicate scientific knowledge gained by the students.

In order to optimize the critical thinking skills, students should be confronted with problems which are designed in the context of everyday life of students, so that students are able to find out for himself while constructing their own knowledge they have acquired through the experience that student. Not only that students must also be involved in digging and asking, activity and determine, collect data and analyze and draw their own conclusions. Students are given freedom in constructing / building knowledge / thoughts and findings during the activity so that students conduct themselves with a carefree, fun and highly motivated (Amin in Khoiliyah, 2006). In this regard, it takes a mature model that is conceptually ready to be implemented. One model of learning mature conceptually ready to be implemented and can facilitate the development of students' critical thinking skills is the generative learning model, combined with hands-on based learning activity. Theoretical base contextual learning science is nothing but the theory of constructivism. The principle of constructivist theory is "activity must always precede analysis". This is why looking for generative learning based learning combined with a hands-on activity.

Model generative learning based on hands-on activity can train students to construct his own knowledge based on new experiences or events associated with the knowledge that he already has a way to gather information and ask, move and find, collect data and analyze and draw their own conclusions that can help students to develop their creativity, to foster the ability to think, move / work and behave and communicate scientific knowledge gained by the students can be optimized through practical activities.