Improving Student’s Mathematical Communication Ability through Think Talk Write Learning Model on Geometry Materials

This study aimed at investigating the students’ mathematical communication abilities on geometry materials through Think Talk Write (TTW) learning model. The type of research was Classroom Action Research (CAR) with data collection instruments are test of mathematical communication skill, lecturer observation sheets, and student observation sheets. This research was given to 31 first-year students of Malang State University in the academic year 2019/2020. This classroom action research stopped at cycle II. Based on the research results obtained, the percentage of students’ mathematical communication abilities in the first cycle had an average value of 68.097% while that in the second cycle had an average value of 82.000%. The average increase from cycle I to cycle II was 13.903%. Based on the results of the study, it can be concluded that Think Talk Write (TTW) learning model by providing material reinforcement in the form of written summaries as material reinforcement at the end of learning can improve mathematical communication skills of first-level students on geometry materials

Introduction thoughts, assumption, and mathematical solutions in order to obtain a better understanding of mathematics (Viseu & Oliveira, 2012). Anthony (2009) in his research offers ten principles of effective education approaches, one of which is student's mathematical communication ability. Students are expected to be able to organize and process mathematical thinking through communication, communicate mathematical thinking coherently and clearly to others, analyze and evaluate mathematical thinking to learn the strategies of others, and can use mathematical language to express mathematical ideas appropriately (Kennedy, Tipps , & Johnson, 2008). Communication needs to be owned by prospective teachers because teachers as the facilitators in the learning process so that the ability is important to improve the ability of students (Mauigoa-Tekene, 2006).
Mathematical communication is important, but students' mathematical communication abilities are still low (Klochkova, 2016;Rahman, 2012;Glava, 2015). Researchers conducted a preliminary study to prospective first-grade teacher students by giving geometry problems to measure mathematical communication abilities including the following.
The observation question asked students to prove that angle 1 was congruent to angle 2. Previously students had been given definitions and related theorems. Following is the answer of one of the students (FK) in the observation. Preliminary study test questions to measure mathematical communication ability of material geometry FK mentioned that ∠1 + ∠m = 90 ° and ∠2 + ∠m = 90 °. FK wrote statements without giving reasons that were appropriate to theorems and definitions. The idea given by FK was not based on good reason. The student had not been able to communicate the definitions and theorems that had been studied previously to answer the questions given.
The previous research states that to improve students' mathematical communication abilities, a learning model is needed. One learning model that can improve mathematical

Result and Discussion
a.
Cycle I The first cycle was carried out with the aim of implementing classroom actions using Think Talk Write (TTW) learning model.

1.
Planning Phase At the planning phase an assessment of the problems found in learning was carried out. At this planning phase the activities carried out were: (a) determining the actions to be taken to solve the problem, namely the low level of mathematical communication of students, especially in geometry; (b) preparing a learning scenario in the form of semester learning plan; (c) preparing the first cycle test questions; (d) preparing lecturer observation sheets and student observation sheets.
2. Implementation Phase After the action plan I was arranged, the next step was implementing the action I according to plan. The stages of the researcher were: (a) giving an opening greeting; (b) praying before learning activities; (c) checking student attendance; (d) conveying the learning plan that would be carried out by applying Think Talk Write (TTW) learning model on geometry material according to semester learning plan; (d) dividing students into five groups; (e) students learned geometry material through group discussions; (f) students wrote the important notes on the results of group discussions; (g) one student was randomly appointed through a lottery to present the results of the group discussion to the class; (g) students made conclusions about the material that had been studied.
3. Observation Phase At this phase, observation of the activities of lecturers and students during the learning process was made. The researchers divided students into five groups to discuss studying material (think). Each group wrote the results of their group discussion on a sheet of paper (write). Students were randomly selected one by one to explain in front of the class about the material being studied (talk). The observation results by the observers were written on the lecturer activity observation sheet and the student activity observation sheet. This research was observed by two observers.

Figure 3
The Answer of one the students in working on test questions in the firts cycle Figure 3 above is the answer of one of the students in working on the test questions in cycle I. Based on the answers, the students had not given reasons that were in accordance with theorems and definitions. The student's mathematical communication abilities were still lacking.
The complete scores of each student can be seen in table 1. During the learning process, other difficulties experienced by students were found including the fact that there were several groups that had difficulty in understanding the language in the source book being studied and the difficulty in bringing concepts in theory into geometrical form. As a result when the students were appointed to explain the concepts that had been learned in front of the class and when working on test questions, students' mathematical communication abilities were lacking.

Reflection Phase
Activities carried out at the reflection stage were analyzing the learning process of the first cycle to find out the increase in students' mathematical communication abilities in learning. The results of the first cycle still did not show the fulfillment of the criteria because the average score of mathematical communication skills in the first cycle was 68.097%. Therefore, it was necessary to carry out action research in the next cycle until the minimum average mathematical communication ability of the student was fulfilled, which was 75.
b. Cycle II 1. Planning Stage Based on observations of the activities of lecturers and students conducted by the observers, things that needed to be improved during the learning process using the Think Talk Write (TTW) learning model could be identified. Next, an improvement was made. The lecturer concluded the material learned through the display of power point text (ppt). The conclusion through this power point text was displayed by the lecturer after the students concluded together in class discussion. The purpose of providing conclusions was as a confirmation and reinforcement of lecturers in writing about the material being studied.
2. Implementation Stage The activities in implementation stage carried out by researchers were: (a) greeting the students; (b) praying before learning activities began; (c) checking student attendance; (d) conveying the learning plan that would be carried out by applying Think Talk Write (TTW) learning model on the geometry material according to semester learning plan; (e) dividing students into five groups; (f) students learned geometry material through group discussions; (g) students wrote the important notes of the results of group discussions; (h) one student was randomly appointed through a lottery to present the results of their group discussion in front of the class; (i) students made conclusions about the material they had learned, (j) the lecturer displayed the power point text to reinforce the material that had been learned.
3. Observation Stage At the observation stage, the observations of the lecturer and student activities in the geometry learning process through Think Talk Write (TTW) learning model were carried out. Based on observations in the second cycle, there were still groups that found difficulties to understand the language in the source book being studied. The lecturer went around to observe and assist the student discussion process. The lecturer provided understanding in easier language for students to understand in groups that were experiencing difficulties. In addition there were also groups that asked about the geometrical meaning of a theorem. Figure 1.4 below is the activity during learning in cycle II. The lecturer went around to help groups who had difficulties during the discussion process in studying the material. The difference between the first and second cycles was in the process of concluding the material that had been studied. In cycle II, the lecturer provided additional media that served as a reinforcement of the material conclusion made by the previous students and provided stabilization of the material that had been studied. The medium was in the form of a written summary of power point text.

Reflection Stage
The activity carried out at the reflection stage was observing the learning process that occured during the second cycle. If the learning activities in the second cycle had shown an increase in students' mathematical communication abilities, then the results of reflection could be used to arrange research conclusions. In this second cycle the average score of students was more than 75. Thus, the study was stopped. In this second cycle the average score of mathematical communication abilities obtained by students was 82.000. Based on data analysis, it was known that the mathematical communication abilities of students in geometry materials had improved. Based on the above table of 31 students, 29 students (93.548%) of the number of students studied experienced an increase in mathematical communication abilities. The following is a bar diagram of an increase in mathematical communication abilities of the first level students from cycle I to cycle II. The average mathematical communication ability of students in the first cycle was 68.097% and the average in the second cycle was 82%. The increase of students' mathematical communication abilities from cycle I to cycle II was 13.903% with an average increase of each student also 13.903%. The increase between cycle I and II was assumed that in the first cycle students were still adjusting to the new learning method namely Think Talk Write (TTW) that was done in this class. Students needed to adjust to their environment. The environment has a role in the learning activities of students, (Henningsen & Stein, 1997). In addition, the researchers added power point text in cycle II, as a medium to conclude the results that were studied. This can increase students' understanding, (Dabbagh & Kitsantas, 2012;Greenhow & Lewin, 2016;Zuana, 2018).

Conclusion
Based on the results of classroom action research, the Think Talk Write (TTW) learning model by providing material reinforcement in the form of written summaries such as power point text as material reinforcement at the end of learning can improve students' mathematical communication abilities. The additional media help as the reinforcement of the conclusions of the material made by previous students and provide confirmation about the material that has been learned. The stages are (a) greeting the students; (b) praying before learning activities begin; (c) checking student attendance; (d) conveying the learning plan that will be carried out by applying the Think Talk Write (TTW) learning model to the geometry material according to semester learning plan; (e) the researcher divides students into groups; (f) students learn geometry material through group discussions; (g) students write important notes on the results of group discussions; (h) one student is randomly appointed through a lottery to present the results of his group's discussion to the front of the class; (i) students make conclusions about the material they have learned, (j) the lecturer displays the power point text as a reinforcement of the material that has been learned.
The results of the study show that of the 31 students studied, 29 students (93.548% of the total number of students studied) experience the increase of mathematical communication abilities. The average mathematical communication ability of students in the first cycle is 68.097% and the average in the second cycle is 82%. The increase in students' mathematical communication abilities from cycle I to cycle II is 13.903% with an average increase of each student also 13.903%.