Optimizing students critical thinking skills related to heat topics through the model of content, context, connection, researching, reasoning, reflecting (3C3R)

The purpose of this study was to determine the implementation of learning by using the 3C3R model and improving students’ critical thinking skills on the topic of heat. The population of this study was all class X of SMAN 25 Bandung, amounting to six classes, the sample was class X MIA6. Sampling used a simple random sampling technique. The research method used a pre-experimental method with a one-group pretest-posttest research design. Data on the results of the implementation of learning with the 3C3R model were obtained from the observation sheet and critical thinking skills of the students’ using essay. The results showed that the average teacher activity was 98.23% with a good category, while the average activity of students was 88.93% in the good category. In addition, there was an increase in students’ critical thinking skills in the heated topic with an N-gain value of 0.65 in the medium category. The results of the hypothesis test show that t-count > t-table (17.25 > 2,045). Thus, there is an increase in students’ critical thinking skills after applying the 3C3R model to the topic of heat.


Introduction
One of the goals of physics in high school is so that students are able to master the knowledge, concepts, and principles of physics and have the skills to develop knowledge, which can be applied in everyday life and as a provision to continue education at a higher level. Students are directed to be critical of natural phenomena that occur around them and creatively solve every problem related to the phenomenon [1]. Thus, physics learning can actually hone the process of complex thinking skills.
Complex thinking is called a high-level thinking process that consists of critical thinking, creative thinking, problem-solving, and decision making [2]. One of the drivers of the advancement of education is to involve critical thinking in learning [3]. Based on the results of preliminary studies through interviews with teachers and students, learning observations and students' Critical Thinking Skills (CTS) test shows that so far teacher-centered learning is monotonous, students lack focus in learning, student curiosity still needs to be explored, active in learning is only dominated by a number One solution to improve students CTS, the Content, Context, Connection, Researching, Reasoning, Reflecting (3C3R) model is a learning model that is oriented to the Problem Based Learning (PBL) approach which has two components, namely core components and processing components. The core components consist of Content, Context, and Connection. This 3C component relates to the content or concept of learning that will be processed by the 3R processing component which consists of Researching, Reasoning, and Reflecting that supports the cognitive process of problem solving and thinking skills possessed by students [4]. The use of the 3C3R model is considered appropriate because this learning model can stimulate students to use their thinking skills and to understand the concepts learned [5].
Learning model Content, Context, Connection, Researching, Reasoning, Reflecting (3C3R) is a new innovation in the Problem Based Learning. 3C3R has a conceptual framework for design problems in the form of model 3C3R theory, focusing on two aspects of the design [4,6].
The critical thinking is to analyze arguments and generate insight into each meaning and interpretation, to develop a cohesive and logical pattern of reasoning, understanding the assumptions and biases underlying each position. Finally, it can provide a reliable, concise and convincing presentation model. The critical thinking is not just logical thinking because critical thinking must have confidence in values, rationale, and belief before logical reasons can be obtained from it [7]. Critical thinking skills developed to refer the indicators put forward by Ennis [8], namely: provide a simple explanation; build basic skills; conclude; make further explanations; strategies and techniques.
Based on several previous studies, it was shown that learning using the 3C3R model could improve students' critical thinking skills [9], students' problem-solving skills [10,11], improve student abilities [12], and student learning outcomes [4]. improve. This research is different from previous research, the application of the 3C3R model is expected to improve students' critical thinking skills on the topic of heat. Besides, the implementation of the 3C3R model at each learning meeting was analyzed using an observation sheet by the observer. The purpose of this study was to determine the implementation of the 3C3R learning model and its effect on improving students' critical thinking skills on hot topics.

Methods
This study used the pre-experimental method with the design of one group pretest-posttest. The selected population is all students of class X SMAN 25 Bandung which consists of six classes, with a simple random sampling technique, selected a sample of X MIA 6 with a total of 37 people. Before being treated, students were given a pretest question in the form of a description of ten questions first to find out the students' initial critical thinking skills in the heat topic. Then the sample was treated in the form of a 3C3R model application. After learning is complete, posttest is given to find out the improvement of students' thinking skills before and after being given treatment.
Before the pretest and posttest questions are used for research, the questions are analyzed first from the aspects of validity, reliability, level of difficulty and distinguishing power. Test results show the level of validity of categorized questions is high. The reliability level of the questions shows a high category. The difficulty test results showed eight medium categorized questions and three easy categorized questions. The result of distinguishing power shows two questions with good distinguishing power, five questions with sufficiently distinguishing power, and three questions with poorly distinguishing power. Students' Critical Thinking Skills (CTS) improvement was obtained from the average gain normalized <g> . The equation to calculate the average gain normalized <g> was presented in equation (1) [13]. .
International The results of the CTS pretest and posttest of students were tested for normality and hypothesis testing. During the learning activities, the activities of teachers and students were observed by observers, with the aim of knowing the implementation of the 3C3R model.
The study conducted three repetitions with a learning duration of 135 minutes. The first meeting discusses the topic of temperature and expansion, the second meeting discusses the topic of heat and the Black principle, and the third meeting discussed the heat transfer. Each meeting is conducted three stages of learning which are opening activities, main activities and closing activities. Implementation of the 3C3R model is implemented in a series of main learning activities. The implementation of 3C3R model learning was observed by the observer using the observation sheet. How to fill in the observation sheet of each meeting by putting a checklist (√) in the "Yes" or "No" column. For the "Yes" column, there are three categories of value choices, 3, 2, and 1. If column 3 is selected, the value is good, if column 2 is good enough, and if column 1 is less good. As for the "No" column, the value is 0. The next steps are as follows: 1) Calculate the total score of teacher and student activity scores that have been obtained; 2) Change the number of scores that have been obtained to be a percentage value; 3) Categorizing the percentage achieved with criteria consisting of 33 <value ≤ 55 (not good); 56 <value ≤ 77 (good enough); 78 <value ≤ 100 (Good).

Implementation of the 3C3R model
Based on the results of the implementation analysis using the learning model Content, Context, Connection, Researching, Reasoning, Reflecting (3C3R) from each meeting experienced an increase. As for each increase can be seen in Table 1. The average teacher activity was 98.23% and 88.93% of students with the implementation category were good. This shows that the implementation of the teacher and students at each stage of the overall data is well implemented [14]. From the data from the observation of teacher and student activities, it shows that at the first meeting most students have not been able to learn actively, either in the stages of researching, reasoning, or in presentation and responding activities. The teacher becomes difficult in giving instructions for changing the stages of learning carried out. Students have not been able to complete the task on time. The learning situation is still familiar with the learning model that is more teachercentered and unfamiliar with the 3C3R model that is applied.
The activities of teachers and students at the second meeting showed an increase. Students begin to be active in learning both at the stages of researching, reasoning, or reflecting. But there is an obstacle at the stage of reasoning connection that is where students do experiments. Teachers have difficulty in the trial activities because each group needs more guidance from the teacher regarding the experiments conducted so that at the second meeting the learning time is almost insufficient. However, learning activities at the second meeting as a whole improved well. At the third meeting, the activities of students were increasingly active when learning took place. Students are familiar with using the 3C3R model. They have understood every step done. Students at the researching stage are very active in seeking information, the reasoning stage has been able to analyze various phenomena in everyday life or from direct observation after the experimental activities. Students show high curiosity so learning takes place very interactively. Overall student activity improved well. In addition, the 3C3R learning model has advantages that can train students to find out (researching), sharpen reasoning (reasoning), and communicate (reflecting) both in terms of content, context, or connection.
The implementation of teacher and student activities at each stage of the 3C3R model is shown in Figure 1.  The stage that reaches the highest value is the stage of researching connection and at the stage of reasoning, content gets the lowest value. At the stage of the researching connection, each meeting students are trained to find information from the demonstrations conducted by the teacher. From the demonstrations they observed, students must be skilled in giving conclusions by connecting the content and context they have found. With the demonstration about heat material, students are more enthusiastic in this learning phase. One of the factors that support the success of learning in improving critical thinking skills, students should be active and directly involved in the teaching and learning process. In line of opinion in states that skills that are repeatedly trained will become habitual or automatic [15].
Students at the content reasoning stage are expected to have the ability to analyze problems related to heat material contained in the student activity sheet. Students tend to discuss the problem more jokingly and there are some students who do not involve themselves actively in discussion activities. As a result learning at this stage is carried out with a low value. In other states that learning is an active process so that if students are not involved in various learning activities like students' responses to teacher stimuli, it is impossible for students to achieve good learning outcomes [16].
Some obstacles encountered in learning when applying the 3C3R model. First, the 3C3R learning model has many stages so it is difficult to instruct each stage to students. Second, students are not accustomed to implementing learning with discussion and practicum methods but are familiar with the lecture method so that students need more time to discuss problem-solving and laboratory. Based on the results of statistical analysis of pretest data with normal and posttest distributions normally distributed so that the hypothesis test uses the t-test at the significance level α = 5%. Hypothesis test results show t-count = 17.25 > t-table = 2.045, it can be concluded that there is an increase in students' thinking skills after the 3C3R model is applied to the heat topic.

2. Improving student's critical thinking skills
The improvement of students' critical thinking skills is because the 3C3R model has advantages that support critical thinking skills, namely the 3C3R process component which consists of researching, reasoning, and reflecting. During the learning process students are trained to look for information in terms of content, context, and connection actively then use their reasoning to solve each problem. Learning is done independently and in groups, where students are trained to learn independently first then join groups to jointly solve problems. Improving students' critical thinking skills in each sub-indicator is shown in the following Figure 2. The sub-indicator of critical thinking skills which has the lowest N-gain value is observing and considering the results of the low category observation of 0.06. This is because students do not have the desire to think further about the results of observations that have been made. Students are said to think critically if they have tried to analyze the argument carefully, look for valid evidence, and produce objective conclusions to be trusted and used as a basis for doing something [18][19][20][21].
The highest N-gain value of 0.88 is found in the sub-indicators of critical thinking determining the action. This is because, at each meeting, students are trained to find information and sharpen their reasoning for everyday events related to the learning material being studied. Students do not feel alienated when given questions to find solutions to events that occur in everyday life related to heat material. Learning will be meaningful for students if they actively interact with concrete objects. This is in agreement with Santoso [15] stating that learning with the development of direct experience and 6 real conditions will produce memorable and long-lasting knowledge. Thus, it is expected that physics learning will be more meaningful.

Conclusion
We have succeeded in conducting research on the application of the Content, Context, Connection, Researching, Reasoning, Reflecting (3C3R) models to improve students' thinking skills related to the topic of heat. The results showed that the implementation of the 3C3R model at each meeting was carried out well and experienced an increase. The average teacher activity is 98.23% with a good category, and the average activity of students is 88.93% in the good category. There was an increase in critical thinking skills students after applying 3C3R models in heat topic. The overall N-Gain value of 0.65 is included in the medium category. Thus the application of the 3R3C model can improve students' high-level thinking skills and can be applied to other physics topics.