Report and Recommendation of Implementation Research-Based Learning in Improving Combinatorial Thinking Skills embedded in STEM Parachute Design Activities Assisted by CCR (Cloud Classroom)

The research aims to compare the advanced class (experimental class) and traditional class with the traditional teaching method. This research is concerned with STEM activity in parachute design. The experiment class applies research-based learning methods integrated with Cloud Classroom (CCR), and the Traditional class is taught using conventional teacher talk or exp lanation. This research used triangulation methods , quantitative, and qualitative methods. The data analysis of the post-test indicated a value of sig (2-tailed) 0.00 where p≤0.05, which implied the student achievement on combinatorial thinking skills criteria in the experimental class was better than that in the control class. The combinatorial thinking skills in experimental class after implementation of RBL was that 16% student were categorized in a low level of combinatorial thinking skills, 39% in medium level and 45% of the student was at the high level of combinatorial thinking skills. The activity of students in the experimental class reached 35 % as the highest activity for very active activity, 27 % active, hesitate 27 %, inactive 6 %, and very inactive 5 %. Based on this result, the implementation of research-based learning integrated with CCR is proven effective in improving student Comb inatorial Thinking skills in STEM activity for parachute design.


Abstract
The research aims to compare the advanced class (experimental class) and traditional class with the traditional teaching method. This research is concerned with STEM activity in parachute design. The experiment class applies research-based learning methods integrated with Cloud Classroom (CCR), and the Traditional class is taught using conventional teacher talk or exp lanation. This research used triangulation methods , quantitative, and qualitative methods. The data analysis of the post-test indicated a value of sig (2-tailed) 0.00 where p≤0.05, wh ich implied the student achievement on combinatorial thinking skills criteria in the experimental class was better than that in the control class. The combinatorial thinking skills in experimental class after imp lementation of RBL was that 16% student were categorized in a low level of combinatorial thinking skills, 39% in med iu m level and 45% of the student was at the high level of comb inatorial thinking skills. The activity of students in the experimental class reached 35 % as the highest activity for very active activity, 27 % active, hesitate 27 %, inactive 6 %, and very inactive 5 %. Based on this result, the imp lementation of research-based learning integrated with CCR is proven effective in imp roving student Comb inatorial Thinking skills in STEM activity for parachute design.

Introduction
The development of increasingly advanced technology requires a person to master various kinds of scientific disciplines in solving problems. Uniquely, in solving this problem, each person has their way that is felt easiest. This implies that there is a specific pattern of resolution done by someone in dealing with problems. This ability is called Co mbinatorial Th inking Skills. The process of thinking combination is part of mathemat ical thin king [1]. On the other side, the ability to thin k mathemat ically is played by the ability of generalizat ion and abstraction [2]. Co mbinatorial Thinking Skills mean that, when faced with a problem, a student tends to solve the problem with various forms of solutions. There are five indicators and several sub-indicators that can be used as a reference to find someone thin king in co mb ination [3] [4]. The first indicator is to identify so me problems, with sub-indicators (a) identifying the characteristics of the problem and (b) applying them in some cases. The second indicator is to understand the pattern of the problem, with sub-indicators (a) identifying the problem solution, and (b) expanding the solution of the problem by taking into account several possibilit ies. The third ind icator is applying mathematical patterns, with sub-indicators (a) applying mathematical patterns, (b) doing cardinality calculations, and (c) developing a settlement algorith m. The fourth indicator is mathematical proof with sub-indicators (a) doing some argument calculation, (b) doing algorith mic testing, (c) developing bijection, (d) doing testing on bijection, and (e) implementing inductive, deductive and qualitative verification. The fifth indicator is considering several other problem co mbinations, with sub-indicators (a) interpreting the problem, (b) proposing several related problems, (c) knowing the new comb ination problem, and (d) finding potential applicat ions in the solution [1] [5]. In this research, Combinatorial Thinking Skills embedded in STEM Parachute Design Activities Assisted by CCR (Cloud Classroom) we develop combinatorial thin king criteria into STEM activity according to Science, Technology, Engineering, and Mathematics section.
The Research-Based Learning (RBL) model of teaching integrates research activities in learning activit ies [6]. In this research, we use the RBL model integrated with STEM activity for Science, Technology, Engineering and Mathematics (STEM ) to improve students' Comb inatorial Thinking Skills. This is because there are still many students who have a good scientific foundation but are lacking in applying their knowledge [7]. STEM is a combination of several scientific d isciplines, and on the other side, interacting with STEM is an important component for learning experience [8]. STEM integration is defined as a combination of science, technology, engineering and mathemat ics in the hope that it can (1) depend on students 'understanding of each discipline in a contextual manner, (2) broaden students' understanding of each discipline in the context of STEM that is culturally relevant and (3) increase students' interest in each discipline by presenting several avenues that students can take to explore each STEM field [9]. In this case, students' responses to the STEM approach hold an impo rtant key in learning. So me predictors that can affect students' perceptions and attitudes towards this approach are motivation, experience, and self-efficacy [10]. Therefore, in learn ing which uses the STEM approach, the implementation of problem-based learning and projects are suggested because the real situation can increase student motivation in participating in learning and can also increase student interest, achievement, and perseverance [11]. The RBL model improves student academics and also builds skills in apply ing previously acquired theories into practice. So, students can fully understand what they are learning [10]. In prev ious research, the RBL learning model can increase student interest in learning the content provided, make them more act ive, more creat ive, and think more crit ically and can imp rove learn ing outcomes [11] [12] [13]. An essential part of this model is that students must know the theories related to the object of research, including Science (Applying principles of relationship between motion, force, and mo mentu m), Technology (selecting appropriate technology to solve problems in parachute design), Engineering (using iterat ive research to solve process and selecting appropriate tools to solve the problems), and Mathematics (solving physical equation in physical section, and using circle fo rmula and Pythagorean theorem to design parachute [14]. There are several steps that must be done by students in conducting research activity in the learning process which explain in Figure 1. In the beginning, students must know what they are going to research and the theory based on relevant sources. After that, initial observations are made in the field by making some evidence in the form of photos or videos. Some other supporting evidence can also be taken into account. Hopefully, students have a picture of co mp letion and consider the results of their deductions using some supporting evidence. So students can interpret the results of research that has been done. Next, students design a solution to a related p roblem. Fro m these results, a conclusion is drawn about the actions they took and reports what was obtained. Another important part of this learning model is that students need help fro m friends formed in a study group. This means that students must work in teams composed of two or more persons who are involved in conducting a study, so that collaboration in teams is needed. The purpose of cooperative learning is to create a s ituation where the success of individuals in the group is indicated as understanding the material, solving problems, and discussion about finding solutions [15]. In a parachute design project, the STEM approach can be used as a solution to make students understand what must be done to solve a problem because STEM integration offers the best way for students to learn a situation in the real world. It is not in the form of parts that must be considered one by one [16]. The effective imp lementation of the STEM approach does not only focus on scientific content but can also arouse curiosity and cognitive reasoning skills accompanied by relevant evidence and understanding and appreciation of the scientific research process [17]. This can be seen in the integration of research activity to solve the problem of students in making good parachute designs. This is because the problems that must be faced by students start fro m the selected design of parachute. In STEM activ ity, an indicator of a good parachute is that we try to drop an egg with a parachute fro m the third floor of build ing into the ground without breaking an egg.

Materials and Methods
This research was conducted to compare trad itional learning with learn ing using the RBL model in STEM activities for parachute design. In its imp lementation, the study applied qualitative and quantitative methods. Quantitative methods are used to analyze student work in solving problems regarding the STEM activ ities for parachute design after being subject to the RBL learning model. Qua litative methods are used to analyze data from the results of interviews conducted with students to find out their opinions about RBL. The independent variable of this study is the RBL learn ing model. The dependent variable is student learning outcomes. After students completed the task, interviews were conducted with the experimental class to find out their opinions about the research-based learning model. The research design used two classes composed of control classes and experimental classes selected by purposive random samp ling and examined using a pre-test and post-test using the following design.   In the design of this study is mix methods which show in Table 1, the two classes used were randomly selected (R). One class is subject to the RBL (X) class, while the other class uses traditional learning. The class subject to a treatment is called the experimental class, while the non-treated class is called the control class. The effect of the treatment is shown ( O 2 : O 4 ) and then analy zed using a t-test, as stated by [18] Figure 2 shows the triangulation model. That picture showed qualitative data with quantitative data to determine the effect of learning model RBL on resolving problems in STEM activities courses. Combinatorial Thinking Skills embedded in STEM Parachute Design Activities Assisted by CCR (Cloud Classroom)

Population
In this study, the people involved were fourth-semester students who studied the implementation of STEM in elementary students. All students were fro m faculty of teacher training and education at the University of Jember. Next, class selection was done through cluster sampling to select two classes. The total number of students in this study was 80 students, with ages ranging from 19-20 years. There were 40 students in the experimental class consisting of 18 males and 22 females. In the control class, there were 40 students consisting of 15 males and 25 females. Data were taken fro m April to Ju ly 2019. To retrieve data, there were several instruments provided. These instruments were tasks, interviews, questionnaires, and observation sheets. Instruments in the fo rm of the task were used to find out the extent of students in understanding the concept of STEM activities for parachute design. The observation sheet was used to determine the level o f student activity. Interviews and questionnaires are used to determine students' opinions regarding research-based learning models.

Instruments
The instruments used in this study consisted of student tasks integrated with CCR (Cloud Classroom), observation sheets, interviews, and questionnaires. The student tas k contained questions about STEM and how to develop a parachute design. Interviews and questionnaires were only given to the experimental class, which consisted of several question items to express the qualitative result. The observation sheet employed Likert scale Very Active (Score 5), Active (Score 4), Hesitate (Score 3), Inactive (Score 2), Very Inactive (Score 1). The instrument sheet was validated by an expert in STEM education.

Tasks
In this study, students in both classes were g iven tasks about parachute design including STEM act ivities. In the experimental class, research-based learning is applied. While in the controlled class, teaching still uses conventional methods. The application of STEM in the design of parachutes can be seen in each of its fields. The field of science requires students to know the concepts of physics regarding the workings of a parachute. The field of technology requires students to find out informat ion about the development of parachutes. The field of engineering requires students to design an efficient parachute. The field of mathemat ics requires students to carry out calculations carefully.
The science and mathematics concept in the development of parachute design is physics and calculus concept. The most important physics concepts that students should understand are (1) kinematics of free -fall mot ion, (2) the concept of dynamics of free-fall motion, and (3) the concept of air friction. Here are so me concepts and equations to understanding science concepts:

Kinematics of Free-Fall Motion in Ideal Conditions
Kinemat ics is subject in elementary physics focuses on motion without analysis about the cause of the motion. There are some concepts in physics like velocity, acceleration (gravitational acceleration), time, and high. (1) Because it is a free-fall mot ion v 0 = 0, equations (1) and (2) Equation (6) in free fall condit ion without init ial velocity (0 m/s) is modified into equation (7) and (8), and equation (8) Technology in STEM activ ities is analyzed and visualizes the data from the experiment to create informat ion and make model processes, entities, and their relationships using structured data. The data interpretation is made using the software, for examp le, Ms. Excel, Matlab, CCR, etc.
Engineering in STEM activity is concerned with goals to generate, develop, and test design of parachute to create the best design solution to the problems of soft landing of an object (egg) fro m height 10 m. Part of design is investigated and making judgment about how the characteristics, properties of materials, length of parachute ropes, shape of parachute, g ive effect on parachute landing. Properties of materials are comb ined with force, mot ion, and energy to create engineered solutions and apply the design of thinking according to creativity and innovation to develop, modify and communicate design ideas. STEM parachute design is shown in Figure 3 below. adt The curricu lu m analysis related to the STEM concept in teaching and learning activity started with the integration between Science concept which is related to Physics Concept. Technology is related to software and computer programming to make simu lation of freefall motion and data analysis. Engineering is about the psychomotor activity to design parachute effectively and efficiently, and Mathematics into one of the topics in an elementary related to a science concept. The purpose of this course was to develop student capability in mathematics and s cience. Parachute Design was chosen as a topic for student STEM activity learning because we hope the student can improve capability in science and mathematics in one set of learning activity.

Finding
The teaching and learn ing process gives the result of implementation RBL in STEM activit ies in the Experiment class compared with the control class that us es traditional method analysis using an independent sample t-test. The result of the pretest score fro m control and experiment class is a normal distribution, which means the class is homogenous. The total number of students in both classes is 80 students (40 student experiment class and 40 student control class). Further analysis is exp lained by statistic software (SPSS). The result of the Pre-test score indicates significant differences between the control class and experiment class, as seen in Table 2.
The significance value serves as the basis to analyze and get a decision fro m the data displayed. The significant value is set at 5 % or 0.05. The average achievement test in the control class is 56.87, with a Standart deviation of 8.52504, and the average achievement test in the experimental class is 59.72, with a standard deviation of 3.71406. The different means of a control class and experimental class are not significant. Table 3 shows the analysis of the pretest fro m the experimental class and control class. The result of the t-test indicates the value od significant (2-tailed) 0.056 with criteria of significant value is 0.05. According to the criteria of homogeneity, statistic means the two classes are homogenous because the value of sig (2-tailed) is bigger than 0.05.

Post-test
The table below (Tab le 4.) d isplays a comparison of post-test results and the mean value fro m the control class and experiment class. Mean from control class reach 73.5750 with Standart Deviat ion value 5.887350 , while the mean of experiment class reaches 80.025 with Standart Deviation value 3.96451. The informat ion fro m Table 5 shows that there is a significant value between two classes indicated with the value of t in Levene's Test score -5.747, according to the value of p < 0.005  Table 5. also shows the result of the independent sample t -test indicating the significant value of 0.000 (p ≤ 0.05). Thus , it is significant. The findings conclude that two classes have differences in terms of student combinatorial thinking test after implementation of RBL is STEM activity to design parachute.
The student activity in the experimental class is analy zed by ten observers using Likert scale student activity spread into five categories very active (score 5), act ive (score 4), hesitate (score 3), inactive (score 2), and very inactive (score 1). The total result of observation student activity is shown in the Figure below.  Figure 4 shows students' activity fro m the experimental class consists of 40 students. The highest score of observation is 35 % of the total student, which indicates during Research-Based Learning imp lementation students very active to cooperate with learn ing process according to combinatorial thinking skills. The second criteria of student activity are 27 % is active level, 27 % are in the hesitate, 6 % in inactive, and 5 % are very inactive. The conclusion is that the implementation of the RBL method is very effect ive in a STEM activ ity in parachute design problems. STEM act ivity in parachute design needs a lot of informat ion about a fact, concept, and theory integrated with STEM information according to Science (Physics), Technology (data interpretation), Engineering (development and modificat ion design of parachute), and Mathematics (calculation related to science concept and data interpretation), Physics is part of science concept including gravitational acceleration, gravitational force, air friction, and velocity of parachute. The mathematics section included formulation with mathematics instructio n.
The result of the pretest score of both class shows the initial capability of both control class and experimental class according to homogeneity and normality distribution of both class. In Figure 5 and Figure 6, the Initial capability of co mbinatorial thin king skills in the control class is 79% in low co mbinatorial thinking skills and 21% in mediu m criteria. Co mbinatorial thinking skills in experimental class data are found at 21% of students categorized in mediu m combinatorial thinking skills and 79% in the lo w category of combinatorial thinking skills .  In tradit ional teaching, only the direct instruction method was used in the teaching and learning process. In traditional teaching and learn ing style, the student is only listening and writing exp lanation fro m lecturer without any excit ing activity. And now in 21 century, we are integrating teaching and learning process helped by CCR (Cloud Classroom) as an interactive website written in HTM L and working in every internet device likes smartphone, PDA, co mputer and laptop, the interface of CCR shown on Figure 7. It facilitates integration between lecturer and student with several features such as text response, emoticon, a mu ltimed ia presentation from CCR database, uploading a picture, sharing link v ideos from youtube [19]. Th is study used CCR to carry out student achievement tests according to the combinatorial thinking category. Lecturer design integration between real class and CCR as flipped classroom swapping research work into classwork. Analysis of content and information supported STEM was also included in the first step to know how deep the student and teacher will do the learning and research activity in one condition.This activ ity depends on student-centered learning and by using CCR student and lecturer have much time to discuss the topics of research. CCR is efficient to carry out the formative assessment (pretest and posttest). Using CCR lectures could make some questions according to comb inatorial thinking criteria and upload questions as open-ended questions.
The result of the post-test score after imp lementation RBL integrated with CCR shows in Figure 8 and Figure 9 that percentages of comb inatorial thin king students in control class and experimental class are increasing. In Control class, combinatorial thinking skills in lo w category reach 16%, medium 39%, and high 45%.
The result shows in experimental class there is 13% at the low level of co mb inatorial th inking, 36% on the med iu m level, and 51% at a high level. According to this data, imp lementation of combinatorial thinking methods integrated with CCR is very useful to improve combinatorial thinking skills in parachute design.  Analysis of Student combinatorial thinking Skills is divided into three categories (low, med iu m, and high) fro m observation result (STEM activity) and post-test score. The researcher takes three student's working tests as a sample to indicated three categories that show student combinatorial thin king skills; each student explains each level. The first work is a lo w co mb inatorial thinking level; second is mediu m co mbinatorial thinking skills and third is high combinatorial thinking skills. Table 6 shows five indicators and sub-indicator of co mbinatorial thinking skills in a STEM activity.
The first worksheet shows students collecting informat ion about parachute design in imp lementation in a STEM activity. After that, interviews were conducted to find out the portrait phase of the students' way of thinking.
Interview is made with the students in this category of combinatorial thin king fro m explorat ion steps of student tasks and making graphs to getting the student portrait phase. The student only performs min imu m steps from all of the indicators categorize in low co mbinatorial thinking skills. The student only performs A 1 (Finding the science concept in parachute design), A 2 (Finding the technology which applied parachute design), ju mp into B 1 (Selecting material for parachute), C 1 (Condition of egg), C 2 (Landing in softly), ju mp into D 1 (Exp laining and analy zing the science concept in parachute design), D 2 (Explaining and analyzing which applied parachute design), and the last steps is E (Considering another design of the parachute). A student worksheet is shown in Figure 10, and Figure 11 is a portrait phase. The second worksheet shown in Figure 12 is mediu m combinatorial th inking skills. The portrait phase of student ( Figure 13) starts from A 1 Finding the science concept in parachute design, A 3 Finding the engineering process in parachute design, B 2 Selecting the shape of parachute, B 1 Selecting material for parachute, B 4 Select ing the length of parachute, B 5 Selecting the materials to save the load (egg), C 1 Condition of egg, C2 (Landing in softly), D 3 Exp laining and analyzing the engineering process in parachute design, E (Considering another design of the parachute).
Science behind parachutes a. Gravity Gravity is the attraction between all particles that have a mass in the universe. The presence of gravity cause a gravitational field.

b. Air resistance
Air resistance is the effect of delay by air obtained fro m objects when moving through the atmosphere. The cause of air resistance is the collision of objects in solid objects with atmospheric gas molecules. The greater the number of air molecules the greater the resistance.

c. Collision
In this parachute design collision concept can occur when after collision objects stick together or there is no reflection at all.

d. Freefall
Freefall mot ion is one straight in one dimension which is only influenced by the presence of gravitational force. The third worksheet shown in Figure 14 is high combinatorial th inking skills. The portrait phase of student ( Figure 15) starts from A 1 Finding the science concept in parachute design, A 2 Finding the technology which applied parachute design, A 4 Finding the mathematics concept in parachute design, A 3 Finding the engineering process in parachute design, B 1 selecting material for parachute, B 2 selecting the shape of a parachute, B 4 select the length of parachute, B 3 Selecting the number of the parachute (single/double), B 5 selecting the materials to save the load (egg), C 1 Condition of egg, C 2 Landing in softly, D 1 Exp lain ing and analyzing the science concept in parachute design, D 4 Exp lain ing and analyzing the mathematics concept in parachute design, D 3 Exp laining and analyzing the engineering process in parachute design and the last steps is E (Considering another design of the parachute).
Change velocity per unit time is called accelerat ion mathematically express: Student oral presentation is one of the important activities to exp ress their level o f knowledge about STEM concepts in parachute design activity. We create eight groups in the Experiment class and control. Each group consists of 5 students. Finally, to know students' knowledge and perception about the imp lementation of research-based learning in parachute design after the presentation process, the s tudents were interviewed with several questions according to parachute design content. The data obtained fro m interviews are discussed below by the teacher and student.
Teacher Student: I'm using the double parachute because a double parachute is more stable than a single parachute. This is related to air resistance.

Discussion
This research exp lores the effectiveness of the showing that the implementation of RBL making the student more crit ical and creative than student taught with traditional methods. Implementation of RBL also appropriate with Sota & Pelt zer (2017) states implementation of RBL imp rove knowledge, competence, cognitive skills, and informat ion technology skills. This research used a cloud classroom for student assessment for pretest and posttest. CCR also had a positive impact on the improvement of student knowledge because CCR facilitates student and lecturer in the online classroom and online assessment process. The integration of CCR in the learning process can help teachers to reduce teaching load, and they can use class time to cover more relevant topics (Liou, 2016). The online assessment using a cloud classroom to facilitate students using a menu, direct question, and quiz. The lecturer can provide interaction with a student, and student can express emotion by using an emoticon, The result of simulat ion fro m co mputer programming is upload by using CCR, and the advantages of using CCR are swapping research work into classwork.
The comb inatorial thinking skills fro m the experimental class were higher co mpared with those in the control class. The result indicates student post-test result which means the experimental class score were significant value and better than control class, because in experimental class learning activ ities used research-based learning wh ich directed student to integrate learn ing and research in one condition. The impact of research-based learning on students has improved their capability to analyze, recognize the information to design parachute in a STEM activity, and get a new design of parachute by using new informat ion fro m the previous information and STEM experiment, develop ment info rmation, and using mathematical methods to analyze each factor in parachute design. RBL facilitates students and teachers to apply research in class and strengthen the academic at mosphere of relationship between teaching and research [20]. Through the Implementation of RBL, the student can make a new design of parachute in improving co mb inatorial thinking skills.

Conclusions
This research result imp lies that implementation of the research-based learning model in STEM act ivity (parachute design) is effective than the traditional teaching model. Imp lementation of the Research-Based Learning (RBL) model makes students more creative in making a new design of parachute with several co mb inations of materials, string, shape, and number of parachutes. This is because the implementation of RBL provides student with research atmosphere in a learning activity with development capability in science, mathematics, and technology capability. Cloud Classroom also gives a positive effect on student assessment in STEM activ ities. In the future, we wish to examine the effect of RBL integrated with CCR at a different section of the STEM project.