The Portfolio Assessment to Teach Writing of Opinion Essay

An opinion essay is a written text to deliver arguments and present supporting evidence to readers. Therefore, this writing activity applies portfolio assessment since it is a cumulative collection of students’ work from beginning to the end. This study aims at describing the implementation of the portfolio to teach the writing of opinion essays at the non-English department in Universitas Muhammadiyah Semarang. The data were collected through observation, tests, and questionnaires. The results showed that the implementation of portfolio assessment could help students write opinion essays by considering its structure and writing components. They were able to state their viewpoint and give supporting data to back up the arguments clearly.


INTRODUCTION
Writing is a language skill. It requires a thinking process (Brown, 2001 as cited in Meiranti, R., 2012). In writing, students need to be able to present their ideas and feelings in a written form. It is in accordance with Harmer (2001) as cited in Trong (2010) writing is the process of expressing ideas, opinions, thoughts, or feelings. Therefore, writing should not be considered a natural gift since this skill can be trained.
As one of English productive skills, experience in the writing process is an effective strategy to produce a piece of writing. This practice will reveal the students' level of spelling, punctuation, word selection, grammar usage, etc. (Pourverdi et al., 2016).
Thus, in the writing process, there are several contexts that represent literacy perspective, knowledge, the technical aspect of writing, characteristics of language, and the difference of linguistic and cultural background (Murshidi, 2014, in Arifatul andBudiman, 2017). The observation and interview results with college students in Semarang showed that they got some difficulties in formulating ideas, conveying opinions, and structuring the thoughts and data into an opinion essay.
In line with the results of the observation above, Suparno (2006) in Wangid (2014) stated writing of opinion essay is a communication activity in the form of delivering written messages to other parties. It means that an opinion essay involves the author as the conveyor of the message or content writing to readers. Further, this kind of writing is an activity that is productive and expressive. Productive and expressive contain the meaning of these two characteristics serves as a conveyor of information. Said to be productive because writing is an activity which is to produce a written work in the form of results from the expression of ideas one's mind. While expressive means the right (able) to provide (expression) images, intentions, ideas, and feelings (Kamal, 2015).
In writing, students are required to be capable apply a number of skills at once. Before writing, students need to make a plan for selecting topics, organizing, and organizing ideas (Abdulai, 2014). At the time of pouring ideas, he stated there are several things that need attention. For example, linguistic aspects such as formation words, diction, and sentences need to be arranged effectively. Spelling and punctuation are necessarily done appropriately and functionally. A number of these skills prove how the complexity of writing skills. The explanation above concludes that students should have understanding and Writing skills, a proper and well-planned writing learning plan with appropriate learning strategies is needed effective and utilizing suitable media with the conditions of students. Therefore, a teacher or lecturer must understand the learning approach to writing and how to develop students' writing skills.
Thus, this current study is intended to apply portfolio assessment in teaching writing of opinion essays. The portfolio assessment encourages students to reflect on the pieces of ideas, opinions, thoughts, etc. in the writing process. As part of the authentic assessment, portfolio assessment can be used as a tool to assess the students' writing. Further, Johnson (1996) in Nezakatgoo (2011) defined a portfolio is as a cumulative collection of students' work. In other words, this assessment shows a student's work from beginning to end. Barton and Collins (1992) as cited in Birin and Baki (2007), stated that portfolios should be authentic, forms of dynamic assessment, and explicit to establish a correspondence between activities and life experiences. This means that portfolios show the students' efforts, progress, and achievement over time, increasing their learning motivation and giving them a sense of autonomous learning. Dealing with the positive effect of portfolio assessment on students' writing ability, it directs them to comprehend the writing aspects such as purpose, content, organization, vocabulary, sentence structure, and mechanics in specific (Boumediene et al., 2016). Based on the definitions mentioned above, the portfolio assessment can be used to encourage students' involvement and improvement since it contains a record of concrete examples of students' work overtime.
Related to the assessment, the following studies show the implementation of portfolio assessment in the teaching and learning process. Abdul (2019); Efendy (2017); Puverdi (2016); Boumediene (2016); and Nezakatgoo, T. (2011) conducted similar studies to investigate the problems and challenges of the university students in writing for an international journal and to investigate the implementation of portfolio assessment to improve students' writing skills and responses. They applied experimental design in their research study. The results showed that the implementation of portfolio assessment could improve the students' writing skills and also give their positive responses by using portfolio assessment. Moreover, another significant aspect of the portfolio assessment is student selfreflection. It can be seen that portfolio assessment can successfully encourage the students to become more active and help them to understand the writing processes. In addition, students are able to improve their writing skills and make their words much worthy as well.
Those researches contributed to this present study by knowing the implementation of portfolio assessment in teaching writing skills. Considering the process of writing and using a portfolio as a method of assessment, this study is aimed to implement portfolio assessment to teach the writing of opinion essays. Setyowati (2016) stated opinion essay helps students to sharpen their critical thinking and logical thinking skills. Therefore, writing an opinion essay is expected to build the students' critical thinking by writing logical opinions, stating the evidence, and drawing the conclusion.

Writing Process
A writer is the center of attention, and the process of writing needs the students to develop a cognitive structure in presenting ideas. Seow (2002) in Azizah (2017) classified the various activities that occur during the writing and identified six major writing processes, including planning, drafting, responding, revising, editing, and evaluating.
Firstly, planning involves generating and organizing ideas in mind, and the goal of writing. Secondly, the drafting stage encourages the writer to focus on the fluency of writing and ignore the draft's grammatical accuracy or neatness. Thirdly, responding intervenes between drafting and revising. It is the teacher's job to give a reaction to student's drafts. Fourthly, revising is not only to check the language errors but also to improve global content and the organization of ideas in order to make the writer's intention clearer to the reader. Fifth, the editing stage gives chance students the chance to edit their grammatical, accuracy, dictation, punctuation, spelling, and add supportive textual material such as quotation marks, etc. Last, evaluating is the time to show students an analytical score based on specific aspects of their writing. Thus, they need to be aware of the criteria for evaluation that should include an overall interpretation of the task (Majid et al., 2012).
Meanwhile, as the components of writing, Jacob et al. (1981) in Anamaryanti (2014) stated 5 components include content, organization, vocabulary, language use, and mechanics. Content is the relevant information about the subject of writing. Organization relates to the generic structure and the sequences of the sentences. Vocabulary is the use of word choices, phrases, or idioms. Language use considers the complex construction, tense, number, article, pronoun, and preposition. Mechanics is the way of using spelling, punctuation, and capitalization.

Portfolio Assessment of Writing
In the writing process, a portfolio can be a set of activities taken on overtime in the development of written products. The main concern of a portfolio in writing an opinion essay is the complexity involved in collections of writing. Therefore, the writing collections need to serve the appropriate grading guidelines, maintain consistency, and avoid subjectivity.
Furthermore, Yancey (1992) in Park (2004) set four principles for implementing the portfolio in writing. 1) Collection; a portfolio is a collection of work, and it is the whole of a student's work. 2) Process; the subset process is one of selection, which is the second principle of portfolios. 3) Reflection; the process by which students explain their learning. 4) Communication; in a sense, a writing portfolio will communicate something about the writer, values, and context in which the writer has worked.
In addition, O' Malley and Pierce (1996) in Rukmini (2017) mentioned the steps in assessing students' writing by using authentic assessment as follows.
(1) Selecting a topic that is appropriate for the students.
Selecting rubrics that students can use.
Sharing rubrics with the students.
Identifying benchmark papers.
Reviewing how students write not just what they write.
Having a conference with the students on their writing results.

Writing of Opinion Essay
Writing an opinion essay requires students to give various arguments or viewpoints on a topic that will defend the thesis statement. Every single point of argument or viewpoint must be supported by evidence or data in the form of research, academic paper, or other trustworthy sources.
Norquist 2015 in Setyowati (2016) defined that an opinion essay contains the writer's opinions or attitudes to influence the readers. Meanwhile, the stated evidence and data are to convince the readers. Thus, the writer needs to present a logical and valid opinion that is supported by facts to support the main idea. Therefore, to write an interesting opinion essay, writers should determine a topic that is related to daily life or things that have been widely known through the mass media such as newspapers, research, TV, online news, etc.

METHODOLOGY
The present study used descriptive qualitative since this study concerned with the processes of a portfolio assessment implementation. The subjects of the study were 75 non-English department students of the third semester in Universitas Muhammadiyah Semarang.
The data were collected through observation, questionnaires, and tests. The observation was conducted to know the students' learning problems in writing an opinion essay to express their ideas and feelings. Meanwhile, the data from the test of writing opinion essays measured the students' writing skills, and the questionnaire was administered to know the students' responses after implementing portfolio assessment in the learning process. The collected data from observation were analyzed and interpreted qualitatively. Moreover, the results of the test and questionnaire were analyzed quantitatively using descriptive statistics based on specific rubrics.

RESULT AND DISCUSSION
In the implementation of portfolio assessment, the English lecturer has arranged the guidance on how to embed portfolio assessment into instructional programs (Gomez, 1999, in Afrianto, 2017. Therefore, the following instructions were used as the teaching strategies that lead students to take responsibility for and reflect on their learning, particularly in the writing of an opinion essay.

Designing the Process of Portfolio Assessment Implementation
The design of this learning process was the combination steps of the writing process and portfolio assessment. In addition, this design was also considered the results of observation. The observation checklist showed that the students got difficulties formulating ideas and conveying opinions in a written form. Other results indicated that the students did not know how to structure their thoughts and data into writing opinion essays.
Furthermore, based on observation data, in every single meeting, students show their progress as the collections of the writing process. The collections of writing process must be in accordance with the structure of the opinion essay. Thus, the lecturer's main role is to check, evaluate, and give feedback to students' writing process.
Before formulating ideas, students need to read some reading topics or articles that are being discussed by most people. They also might do observations or even watch videos that contained controversial issues. Those activities build their critical thinking to formulate ideas by analyzing the problems that existed there. After that, they try to write their opinions into written form. Write several interesting points got from the sources. Table 1 Structure of Opinion Essay

Structure Information Title
Ask yourself whether you agree or disagree with the topic. Title contains one complete sentence or a question.

Introduction
Introduce your essay by giving a brief definition the topic and stating your thesis statement.

Opinions/ arguments/ ideas
 State your reasons why you agree or disagree with the topic.  Use phrases such as I think…, in my opinion…, the first thing to consider is…, as far as I'm concerned…, etc.

Evidence/data/ example
Give the supporting evidence/ data/ example to back up your opinions.

Conclusion
 Conclude the essay by restating your opinions with different words and give the summary for two or three arguments.  Use phrases such as to sum up…, in conclusion…, in spite of…, in order to…., etc. In addition, to convey the opinions into written form, students should consider the components of writing skill as follows.  Content must be very in accordance with the title and it states the relevant information about the subject of writing. Organization The harmony of text must be very precise since it relates to the generic structure and the sequences of the sentences. Vocabulary The selection of vocabularies must be very appropriate by considering the use of word choices, phrase, or idiom.

Language use
The use of language considers the complex construction, tense, number, article, pronoun, and preposition.

Mechanics
The neat and easily readable are prioritized, and it considers the way of using spelling, punctuation, and capitalization.
After the structure of the opinion essay and the rubric of the writing process were well prepared, then the next was implementing

The Implementation of the Portfolio Assessment in Writing Opinion Essay
In implementing portfolio assessment, the steps of writing an opinion essay were obtained from observation results. Therefore, implementing portfolio assessment as a cumulative collection of students' work showed their work from beginning to the end. It was also to encourage them to reflect on their ideas, opinions, and thoughts and present the supporting data in an opinion essay.

Formulating the title and Stating the Introduction
After gathering information from some sources, the students formulated a title as the topic in their opinion essay. The title consisted of one simple sentence that contained agree or disagree point about the topic. Moreover, the title might be a question form since it referred to a controversial issue that fully attracted readers' attention to read the opinion thoroughly.
Meanwhile, to state the introduction, students define the main idea that would be being discussed. This part was a roadmap that gave a hook to engage the readers with the topic. After that, they stated one or two thesis statements to emphasize the topic stated in the title. The thesis statements were to prepare the readers to dip into the essay. Further, the lecturer checked and gave suggestions to every student.

Generating Ideas/Opinions
In generating ideas or opinions, the students write several points from some sources of research articles, newspapers, or videos of controversial issues. The opinions should be objectives since the problems had existed there.
The ideas stated their reasons why they agree or disagree with the topic. Thus, they not only write the information but also convey their expressions to mind. The opinions consisted of three to five points that were related to each other. In other words, the students were allowed to give criticism or praise to the topic. To make sure that all students had clearly expressed their thoughts in a precise manner to provide opinions to the issue with reasonable logic, the lecturer gave comments to their writing and all students collected these opinions as to the process of writing.

Stating Evidence and Data
To support the opinions stated in the generating ideas part, students gave a logical explanation and showed relevant evidence or examples and data. The logical explanation contained facts taken from some sources. Meanwhile, the data might be from the result of analysis by experts or research articles. This part was really fundamental since evidence and data could be used as the validity of the opinion essay. Therefore, the lecturer controlled the students' writing in terms of content and language use for this part.

Drawing Conclusion
In the last part, students draw a conclusion that wraps up their essay. This summary covered all the opinions and data to easily understand the arguments. In addition, the students restated their opinions using different words. Further, the lecturer checked all students' work and made sure that they had completed the writing according to the structure of the opinion essay and the components of writing.

Presenting the Opinion Essay
This phase asked students to present their opinion essay on online social media as the submission of portfolio assessment. Hence, the lecturer did an evaluation and gave scores to the students' work. The table above showed that in terms of content the students got 83.12, which was meant they were able to formulate the title clearly and state the relevant information about the topic of the opinion essay. The term of organization, students got 83.33. They could arrange the opinion essay based on generic structure and the sequences of the sentences cohesively. Further, they got 77.56 in terms of vocabulary. Most students used appropriate word choices and phrases related to their opinions in their essays. In terms of language use, the students' mean score was 79.42 and it was meant that they were able to use tense, article, pronoun, and preposition properly to state the opinions and present the supporting data. The last, the students got 80.81 in terms of mechanics. It was meant that their opinion essay was neat and easy to understand since it showed good spelling, punctuation, and capitalization. The findings were relevant to the study conducted by Setyowati (2016) that opinion writing can improve a person's thinking ability. Through writing, someone can express the feelings and arguments that are desired by the public. An opinion essay may also contain someone's peeling opinion to resolve a particular issue of an actual nature or controversy with the aim to inform the readers.

Students' Reflection towards the Implementation of Portfolio Assessment
The process of implementing portfolio assessment to teach the writing of opinion essay run effectively. It was seen in the results of the questionnaire. The students were enthusiastic to write an opinion essay using portfolio assessment. They showed their efforts, progress, and achievement over a period of time during writing an opinion essay. This learning activity could increase their learning motivation and also give them a sense of autonomous learning. It is relevant to the previous study of portfolio assessment conducted by Efendy et al. (2017) that this assessment serves various collections of information or documentation of students' work taken during the learning process within a certain period of time and stored in a bundle systematically.

CONCLUSION
In conclusion, the authentic assessment of portfolio has been successfully implemented to teach the writing of opinion essays. Its implementation could help students to write opinion essays by considering its structure and the components of Available online at http://journal.unnes.ac.id e-ISSN 2460-853X 335 writing. They could write an interesting opinion essay by determining a topic that is related to daily life or things that have been widely known through the research article, mass media such as newspaper and online news, and YouTube video contained controversial issues. Further, they were able to state their viewpoint and give supporting data to back up the arguments clearly.
In other words, the portfolios can be easily used to document students' writing progress. It shows a collection of the work of a student, as a result, implementation of performance tasks to achieve learning goals, or achieve competencies specified in the curriculum. Thus, realizing the writing process is very important to develop their critical thinking, attitude skills, and their expression towards something.