Improving Chinese Reading and Writing Skills: Second Language Acquisition Theory Perspective

This research aimed to study the theories and principles for improving Chinese reading and writing skills based on second language acquisition theory and investigated the factors affecting Chinese major students’ reading and writing skills for university students in


Introduction
The 21 st century is a highly competitive era that requires international cooperation and communication with the global society.Chinese has always been one of the six working languages of the United Nations.Due to the rapid development of China's economy, Chinese has also become a popular language in the world.According to the 20 years national development strategy of the National Education Plan 2017-2036, if Thai people have knowledge of Chinese as a tool for communication and cooperation in business, trade, and development in various fields effectively, Thailand will have a competitive advantage over other countries in the region (Office of the Education Council: ONEC, 2017).Consequently, learning Chinese is very significant in careers for Thai people, as well as for the economic development of Thailand.According to research results from the center for China studies institute of Asian studies at Chulalongkorn university, Chinese major students in Thailand could not use Chinese well after graduation and lacked proficient Chinese language skills (Wasinanon, 2016).
In the International Curriculum for Chinese Language Education of Office of Chinese Language Council International: TOCLCI (2014), Chinese language proficiency level for learners studying Chinese as a second language or foreign language is divided into three levels beginner, intermediate, and advanced, which corresponds to Chinese Language Proficiency Test (Hanyu Shuiping Kaoshi: HSK) divided into six levels.The beginner level includes HSK 1-2, the intermediate level includes HSK 3-4, and the advanced level includes HSK 5-6.Currently, Chinese majors in most higher education institutions in Thailand set passing HSK 4 or 5 as one of the graduation requirements (Office of the Education Council: ONEC, 2016).Based on the score analysis of HSK from the Confucius Institute at Mahasarakham University in 2019-2020, it was found that for HSK 4, the average score of listening was 66.20, reading had an average score of 61.95, and writing had an average score of 53.56.For HSK 5, listening had an average score of 66.79, reading had an average score of 51.11, and writing had an average score of 55.38.The above data showed that learners' Chinese reading and writing skills have not yet reached the standards set by the curriculum.Moreover, developing Chinese reading and writing skills should be emphasized at higher education institutions in Thailand (Zhong, 2019).
Learning Chinese in Thailand is learning a foreign language or a second language which emphasizes skills-centered training with the transfer of language knowledge into language skills by using a comparative approach between the target language and the first language (Liu, 2016).In teaching Chinese as a second language or foreign language, the teachers, teaching materials, and teaching methods are the most important factors.Teachers should use effective and appropriate teaching methods for learners in order to help them achieve their learning goals effectively.Chinese reading and writing skills are advanced skills for learners, and good reading and writing skills require long-term systematic training (Zhao, 2016).In addition, second language acquisition theory can provide guidelines for teaching and learning Chinese for Thai students.
At present, there is still a small amount of research on developing reading and writing skills in Chinese as a second language for Thai undergraduate students.Chinese reading and writing skills are advanced skills that are affected by various factors.As a teacher with ten years of Chinese teaching experience in northeast Thailand, the researcher found that there are many challenges and obstacles in teaching Chinese reading and writing skills.Therefore, this study was focused on seeking answers to the following research questions and research objectives.

Research Questions
(1) What are the appropriate theories and principles for improving Chinese reading and writing skills based on second language acquisition theory for university students in northeast Thailand?
(2) What are the factors affecting Chinese major students' reading and writing skills in the northeast of Thailand?

Research Objectives
(1) To study the theories and principles for improving Chinese reading and writing skills based on second language acquisition theory for university students in northeast Thailand.
(2) To study the factors affecting Chinese major students' reading and writing skills in the northeast of Thailand.

Reading Skill in Chinese as a Second Language
Reading is a process of extracting information from symbols.It is the process by which people obtain information by using visual organs and processing the information from the brain to understand the meaning of symbols (Xv, 2007).Additionally, reading skill is the ability to receive information from what is read, including the ability to memorize words, guess the meaning of unfamiliar words, understand sentences, phrases, and comprehend the articles (Zhai, 2010).Due to the uniqueness of Chinese characters, reading Chinese as a second language is an advanced skill.Zhao (2016) has divided reading Chinese as a second language into intensive reading and extensive reading, which have different purposes and speed requirements.Intensive reading is a practice of overall language proficiency, which requires understanding detailed information, and extensive reading is a practice of obtaining specific information as required.
In this study, reading skill in Chinese as a second language refers to the ability to interpret Chinese characters through a thinking process to understand the information from reading.There are multiple levels of reading skills in Chinese as a second language, ranging from characters, words, sentences, and paragraphs to articles.Yang (2010) stated that reading skill in Chinese as a second language has two components: comprehension and techniques.Comprehension means understanding words, sentences, the main purpose of the paragraph, and the author's attitude.Techniques include guessing the contextual meanings of characters or words, comprehending long and complex sentences by using conjunctions, catching keywords, and skipping unimportant words.Zhou (2017) pointed out that word frequency and context, sentence comprehension, textual understanding, schema, and inference were important issues in developing reading skills in Chinese as a second language.According to Lv (2007), the development of reading skills in Chinese as a second language at different levels should have different content and methods.Chinese character recognition and vocabulary understanding training should be focused on beginners.Vocabulary knowledge, comprehension of sentences and articles, as well as guesswork skill and skipping techniques, should be focused on the intermediate level.
Articles in different genres should be selected according to the professional needs of learners in order to respond to future careers at the advanced level.

Writing Skill in Chinese as a Second Language
Writing is literal communication to convey knowledge, thoughts, emotions, experiences, news, and imaginations from the author to the reader (Laksiri, 1997).It is a composite process consisting of planning, translating, and reviewing (Zhang, 2006).Writing skill is the ability to express opinions in a private language, including language expression ability, cognitive ability in observation, and analytical ability (Zhao, 2016).There are many types of writing.The institute of English language (2015) stated that content, form, grammar, style, and mechanics were five components in writing and divided writing into four categories: mechanical copying, controlled writing, less-controlled writing, and free writing.
In this study, writing skill in Chinese as a second language refers to the ability in the process of transcribe knowledge, information, experiences, or expressing thoughts, emotions, and feelings into Chinese characters to convey meaning to others.Zhai (2010) expressed that knowledge of the language system, including the use of vocabulary, grammar appropriate according to different article formats and contexts, knowledge of the logical relationship between sentences and the connection between paragraphs, and fundamentals of Chinese writing, including the correct use of punctuation and writing styles of various essays should be involved in the development of writing skill in Chinese as a second language.
Zhao (2016) pointed out that reading sample essays to collect vocabulary and sentence patterns is a good way to promote writing skill in Chinese as a second language, and limited imitation can avoid negative transfers from the mother tongue or first language.According to Lv (2007), the development of writing skills in Chinese as a second language at different levels should have different content and methods.Using words and sentences correctly by imitation practice should be focused on beginners.Writing Chinese in daily life, such as letters, notes, greeting cards, invitations, announcements, the diary should be focused on the intermediate level, and teachers should provide templates for learners.At the advanced level, teachers should develop learners' ability to use formal language writing for work, such as contracts, memorandums of understanding, manuals, product introductions, work summaries, speeches, and documents.

Second Language Acquisition Theory
Second language acquisition theory refers to concepts or principles for learning a second or foreign language, which explains how people acquire languages, especially foreign languages, and interprets the process of learning a second language or foreign language from different perspectives.

Sociocultural Theory
The sociocultural theory of the former Soviet psychologist L.S. Vygotsky emphasizes the important role of social relations and cultural structures in the development of human learning and thinking, and language plays a very important role in the process of developing cognition.Geerson (2012) stated that a language is a tool for learning and creating ideas in Vygotsky's view.Susan (2008) revealed that contextual language should be emphasized, and internal processes should be involved in the acquisition of a second language.Mediation, regulation, internalization, and zone of proximal development are the main concepts in sociocultural theory.Lantolf and Thorne (2015) were key figures in advocating the relationship between sociocultural theory and second language learning.In Lantolf and Thorne's Sociocultural Theory and the Genesis of Second Language Development (2015), mediation is the process by which humans invent objects, things, and ideas.As the main form of mediation, regulation is divided into three stages: object-regulation, other-regulation, and self-regulation (Susan, 2008).In foreign language or second language learning, object-regulation refers to the adjustment under the influence of the external environment, other-regulation is the cooperative learning of students with the help of teachers and peers, and self-regulation means that students can rely on their own abilities for self-study.Internalization refers to a phenomenon caused by the influence of social environments, which has the process of absorbing or assimilation and accommodation until transforming into own internal knowledge (Lantolf & Thorne, 2015).Internalization in second language learning stems from imitation in interaction, it's not a simple copy, but it's a creative process.Vygotsky believed that cognitive development occurs through social activities and interpersonal interactions, and all learners have the potential to develop with the help of others (Lantolf & Thorne, 2015).In teaching a second language, teachers should provide scaffolding within student's zone of proximal development and create a zone of proximal development in the next step for learners.Furthermore, dynamic assessment should be used as the main method of assessment in second language teaching and learning based on sociocultural theory.In addition, Rosamond (1998) proposed that self-regulation, small group interaction, and scaffolding in the proximal development zone should be applied in second language learning.

Monitor Theory
In 1985, American linguistic educator Krashen proposed the monitor theory for second language learning, which consists of the acquisition learning hypothesis, the natural order hypothesis, the monitor hypothesis, the input hypothesis, and the affective-filler hypothesis.Liu (2016) revealed that the input hypothesis is the most important hypothesis in Krashen's monitor theory.In second language learning, comprehensible input which should not be too hard or too easy and should be based on i+1 mode (i means the learner's current language level), is very important; when learners understand the input, language acquisition will occur spontaneously (Liu, 2016).The affective-filler hypothesis is another important hypothesis in monitor theory, which discusses the emotional factors affecting second language learning success, such as motivation, attitude, self-efficacy, and anxiety (Liu, 2016).Krashen believes that comprehensible input and positive emotions are two factors for success in learning a second language.That means comprehensible input plus a low anxiety learning environment can effectively aid second language learning, which is the fundamental principle of Krashen's theory of second language acquisition (Liu, 2016).

Contrastive Analysis Hypothesis
In 1957, a linguist from America named Robert Lado proposed the contrastive analysis hypothesis, which believed that teaching and learning a second language can be done by comparing the target language with the first language (James, 1980).Learning a second language is the result of habitual stimulation and reinforcement; in the process of learning a second language, learners will be affected by their first language habits, such as phonetics, vocabulary, and grammar.This is called language transfer (Liu 2016).Transfer can be divided into positive transfer and negative transfer.Positive transfer is caused by the similarity of the two languages, which plays a positive role in second language learning.Negative transfer is caused by the difference between the two languages, which cause obstacles to learning a second language (Liu, 2016).Susan (2008) summarized that learning the differences between the first and second languages is more important and necessary than learning the similarities between the two languages because the first language is the main source of errors and mistakes in second language learning thus differences between first and second language can be a solution for error analysis.James (1980) proposed contrast analysis can be applied in teaching and learning second language learning, such as predicting errors and mistakes that learners may make, defining the scales of learning difficulty, diagnosing and analysis errors that have occurred, and set to incorrect options for multiple-choice in exams.

Factors Affecting Reading and Writing Skills in Chinese as a Second Language
Liu (2016) divided the factors affecting second language learning into internal factors and external factors.Internal factors include age, intelligence, language ability, learning strategies, communication strategies, metacognition, learning style, motivation, personality, attitude, and anxiety, etc.; external factors mainly refer to language environment, including social environment and classroom environment.Zhai (2010) discussed the factors that affect reading skills in Chinese as a second language and believed that insufficient word count is the biggest obstacle to reading Chinese.In addition, insufficient grammar knowledge, unfamiliarity with Chinese language expressions, and lack of relevant basic knowledge are the main factors.According to Zhang (2006), meta knowledge, the ability to compose, and the ability to write in the first language are the main factors affecting writing skills in Chinese as a second language.In addition, writing training and self-confidence in writing are the latent factors.In this study, the researcher analyzed and synthesized relevant articles and listed the factors that affect second language reading and writing skills as follows:

Vocabulary
Vocabulary is the sum of words in a language system (Zhao, 2016).It is one of the three components of a language and is an important part of language learning (Zhou, 2017).Vocabulary doesn't just include words but also phrases, expressions, proverbs, etc. (Wan, 2016).Vocabulary is the building material of language and is the basic unit of a sentence.Without it, information cannot be transmitted, and communication activities cannot take place (Liu, 2016).Hence, vocabulary plays a very crucial role in language learning.

Grammar
Grammar is one of three components of a language, which is a structural rule of words, phrases, and sentences in a language.It is a linguistic rule that people must follow when communicating in a language (Zhang, 2010).Grammar is the rule of making words or composing sentences in a language, which consists of rules for word formation and rules for sentence formation (Shi, 2011).

Teaching Method
The teaching method is a process in which teachers design various activities to enable learners to acquire knowledge, skills, or ideas according to learning objectives (Khamanee, 2012).Teaching methods are behavioral approaches in teaching and learning activities for learners to achieve their learning goals, which include the teaching methods of the teachers and the learning methods of the learners.Language teaching methods can be divided into three levels: teaching principles, teaching steps, and teaching techniques (Zhao, 2016).

Language Environment
Language environment refers to everything around involved in learning a language, including the social environment and classroom learning environment.The social environment can be a natural resource for learning and imitating language for learners, which enables students to use what they have learned in real situations.The classroom learning environment refers to all input information and classroom atmosphere, including textbooks, exercises, and all learning activities (Liu, 2016).

First Language
The first language refers to the language that a person experiences and perceives after birth, which is naturally derived from parents.Generally, the first language is usually the mother tongue, except for some immigrants (Zhou, 2017).Second language learning is often affected by the first language, which is called transfer.Language transfer can be divided into positive transfer and negative transfer.The positive transfer comes from the similarities between first language and second language, which usually plays a positive role in second language learning.The negative transfer comes from the difference between the second and first languages, which usually cause errors and barriers in second language learning (Liu, 2016).

Motivation
Motivation refers to the internal driving force that enables people to strive to achieve a certain purpose and determine the behavior's direction and goal.It is often expressed as a desire to satisfy one's own needs, including both physical and mental needs.The motivation for second language learning can be divided into integrative motivation and instrumental motivation.Integrative motivation is motivated by intrinsic liking, which has the goal of learning to communicate directly with native speakers and have more contact with the target language culture.The instrumental motivation is the practical purpose of using a second language as a tool, such as access to information, education, occupation, raising social status, etc. (Liu, 2016).

Attitude
Attitude refers to a person's feelings about things or other people, which is generally expressed as liking or disliking, acceptance or non-acceptance.Attitude consists of cognitive components, which is the knowledge and understanding of something or a person in order to evaluate, and affective components which is a feeling or emotion about something or a person, such as satisfaction or dissatisfaction, need or needs, good or bad, and behavioral component which is a person's readiness or inclination to act (Wongsanut, 1991).

Interest
Interest is an individual's attitude and tendency to explore something and engage in a certain activity, also known as a "hobby," which is a manifestation of personality tendency (Che, 2001).Individual interests depend on their own needs, which means interest only arises when needed.Interests can be divided into the direct interest, which refers to the interest in the process of activity, and indirect interest, which refers to the interest in the outcome of the activity process (Li, 2014).
2.4.9Self-efficacy Self-efficacy refers to a person's perception of their own related abilities.It is a belief in one's own ability to successfully complete a task.There are three dimensions of self-efficacy.The first dimension is the difficulty with which a person thinks they can achieve success.The second dimension is the confidence to achieve the goals.The third dimension is confidence in one's own abilities in similar or different fields (Zhou & Guo, 2006).

Anxiety
Anxiety is an unpleasant emotional state caused by a person's concern about something uncertain or an imminent danger or potential threat, such as nervousness, shaking, worry, being upset, etc. Anxiety in learning a second language is usually manifested in three aspects: communication anxiety, test anxiety, and anxiety about the negative evaluation of others (Liu, 2016).

Research Design
Documentary and survey research were used in this research study.The resources for documentary research were derived from books, theses, academic papers, and research articles related to teaching Chinese skills as a second language from the perspective of second language acquisition theory.A mixed method research including quantitative and qualitative research was used, which can overcome the limitations of a single data collection method and deepen the understanding of the research question (Creswell, 2014).The scope of the population for the survey research was 2,145 Chinese language major students and 55 Chinese language lecturers at 12 universities in northeast Thailand.

Data Collection
The study was divided into three stages as follows: In Stage 1, the theories and principles for improving Chinese reading and writing skills based on second language acquisition theory for university students in northeast Thailand were studied by analysis and synthesis, including 34 thesis, academic papers, and research articles that related to teaching second language skills from the perspective of second language acquisition theory.
In Stage 2, the components of factors affecting Chinese major students' reading and writing skills in the northeast of Thailand were studied.The sample groups used in this stage were 386 Chinese language major students who had passed HSK3 or higher level at 12 universities in the northeast of Thailand selected by voluntary selection.The instrument was a questionnaire with a reliability of 0.733, affirmed by five experts in the area.
In Stage 3, the factors affecting Chinese major students' reading and writing skills in northeast Thailand were studied to reveal the current situation in the context.The sample groups used in this stage were 9 Chinese language major students who had passed Chinese HSK4 and 3 Chinese language lecturers with more than five years of teaching Chinese reading and writing skills at universities in the northeast of Thailand selected by purposive sampling.The instruments consisted of an interviewing form for investigating factors affecting Chinese reading and writing skills for the students, an interviewing form for investigating factors affecting Chinese reading and writing skills, and guidelines for developing the instructional model for the lecturers, affirmed by five experts in the area.

Data Analysis
The data obtained from the documentary research were analyzed by content analysis.The data obtained from questionnaires were analyzed by exploratory factor analysis with a computer program.The data obtained from the interview were analyzed by content analysis.

Results
The results of the study are shown according to the objectives of the research as follows: From Table 1, it was discovered that sociocultural theory had the largest number of applied research in second language skills teaching, followed by monitoring theory, contrastive analysis hypothesis, and universal grammar theory had the least applied research.

To Study the Theories and Principles for Improving Chinese Reading and Writing Skills Based on Second Language Acquisition Theory for University Students in Northeast Thailand
The results of the study by content analysis revealed that there were many theories and principles that study methods and approaches to acquiring a second language from different perspectives.Currently, the sociocultural theory is the trend in teaching and learning research based on second language acquisition theory for the development of second language skills, especially in reading and writing skills.In addition, monitor theory and contrastive analysis hypothesis are also significant for the development of second language skills.From content analysis, the concepts and principles for improving reading and writing skills in Chinese as a second language were proposed as follows: Teaching and learning based on Vygotsky's sociocultural theory emphasize the importance of using language in interactions as mediation to construct the self-knowledge of learners.This process is called internalization, and teachers should improve the language skills in each student's zone of proximal development.This teaching and learning management focuses on the development of individual differences, and dynamic assessment should be used rather than non-dynamic assessment.
Language knowledge should be focused on the internalization process, such as Chinese vocabulary and grammatical knowledge.At the same time, inductive teaching is an effective method that can help second language learners to summarize conceptual knowledge by themselves, and teachers are responsible for guiding and providing help when needed.In addition, cooperative learning and peer evaluation play an important role in the application of language knowledge and skills.
It should be considered that there were many factors, including external and internal factors, in the process of constructing second language knowledge and transferring language knowledge to language skills; the input hypothesis and the affective filler hypothesis in Krashen's monitor theory should be referenced.
It cannot be ignored that the target language learning of adult second language learners would inevitably be affected by their first language, both positively and negatively, and Lado's contrastive analysis hypothesis could provide theoretical guidance in linguistics for analyzing errors that second language learners make when using the second language.From Table 2, it was revealed that the appropriateness of the variables was at a high level, and the variables were related and could be analyzed by exploratory factor analysis.From the interviews with students, it was noted that the results were as follows:

To Study the Factors Affecting Chinese Major Students' Reading and Writing Skills in Northeast Thailand
(1) The vocabulary of the students at the high level was more than 2000 words, the moderate level was 1000-1200 words, and the low level was 600-1000 words.In addition, the students at the high level had higher abilities in the use of Chinese words than the students in the other two groups.
(2) The students at the high level had a good ability to analyze Chinese sentences, while the students at the moderate and low level had a poor ability, and most of them relied on guessing to help to understand.When making sentences, students at the high level could directly use words to form sentences according to their own sense of the Chinese language, while students at the moderate and low-level habitually wrote sentences in Thai first, then translated them into Chinese.
(3) All three groups of students indicated that there was not any Chinese environment around.However, students at the high-level used online resources and social entertainment activities to practice Chinese in their daily life.The students at the moderate and low levels were only able to use Chinese in the classroom.
(4) All three groups of students considered listening and speaking to be more interesting than reading and writing.But students at the high level wanted to read and write an interesting story and could force themselves to read and write on content that they were not interested in when necessary.In comparison, moderate and low levels students did not want to read or write.In addition, students at the high level and moderate level were more likely to use Chinese to communicate with others and post on social media than students at the low level.
(5) The three groups of students had different occupations.Students at the high level wanted to work as interpreters or translators and agreed that this requires high Chinese reading and writing skills.The moderate-level students wanted to pursue careers that use listening and speaking more than reading and writing, such as travel-related careers.It is worth thinking that low-level students wanted to be Chinese teachers in Thailand.
(6) All three groups of students felt nervous, stressed, and worried before the reading and writing exams.When communicating in Chinese, the high-level students were more confident than the moderate and low-level students.The moderate and low-level students were worried that others could not understand what they wanted to express and preferred to communicate in Thai.Interestingly, none of the three groups of students were concerned about negative comments from others, and they agreed that it was a good opportunity to learn.From the interviews with lecturers, the results were as follows: (1) Vocabulary count and proper use of the vocabulary were very important for Chinese reading and writing skills.In that case, teachers needed to increase their vocabulary.In teaching Chinese, the teacher must explain the words clearly by comparing Chinese and Thai with examples or situations.In addition, teachers should cultivate a love of learning Chinese and help students accumulate vocabulary in daily life.
(2) Knowledge of Chinese grammar was essential for undergraduate students.Thai and Chinese both have similarities and differences.As a result, a comparison of Thai and Chinese grammar by describing example sentences in various situations could help students understand Chinese grammar better.Besides, teachers should strengthen the students' Chinese thinking ability or Chinese senses.
(3) The northeast of Thailand lacked a Chinese environment.However, now students could learn from Chinese movies, dramas, or shows and could use Chinese in projects, for example, language and cultural exchange with Chinese, participation in an event or competition, etc.Additionally, teachers should create opportunities for learners to practice and apply their knowledge, and sharing knowledge and experiences with peers is a good method.
(4) Reading and writing were related to Chinese characters, which was a difficult point and obstacle for Thai learners.Furthermore, teachers should use different methods to promote positive attitudes of learners, for instance, creating a fun and relaxed learning atmosphere, organizing various activities to stimulate the interest of learners, and using peer-to-peer learning methods, etc.
(5) Occupation was related to specific competence in the Chinese language; to illustrate, the guide would focus on listening and speaking.Furthermore, translators must be good at reading and writing.Moreover, those who wished to apply for a scholarship to study in China were clearly better at using the language than others because of diligence, patience, and enthusiasm.
(6) Students were worried about communicating in Chinese.They felt pressure and were nervous before taking the exam.At the same time, few students worried about negative comments from others.Therefore, teachers should have ways to reduce student anxiety, which could be seen by allowing students to work in groups, creating a relaxed atmosphere, using humorous or encouraging words instead of criticism, and focusing on the dynamic evaluation rather than the exam, etc.  From Table 6, it was revealed that the results from the data analysis of questionnaires, the interviewing form for students, and the interviewing form for lecturers to be consistent.It could be concluded that the factors affecting Chinese major students' reading and writing skills in the northeast of Thailand consisted of vocabulary, including vocabulary size and vocabulary usage, grammar knowledge, language environment including learning from online resources and practicing Chinese in exchange, attitude including Chinese usage in daily life and Chinese usage in social media, motivation including future career planning and interest in applying for a scholarship, and anxiety including exam anxiety, communication concerns and difficulties in learning Chinese.

Discussion
This research theoretically studied the reading and writing skills of Chinese as a second language from the perspective of second language acquisition and investigated the factors that affect Chinese reading and writing skills for Chinese major students in northeast Thailand.The findings could be discussed as follows.
In this study, the researcher studied theories, concepts, and principles to discover guidelines for developing an instructional model that could promote Chinese reading and writing skills for Thai undergraduate students.It revealed that Vygotsky's sociocultural theory, Krashen's monitor theory, and Robert Lado's contrastive analysis hypothesis were appropriate to develop the instructional model.According to the sociocultural theory, language is a symbolic human invention that can mediate between people and surroundings.Learning a language is cognition that comes from experience and interaction with others and society.Sociocultural theory is important to language learning and teaching, which focuses on learning with interaction under the scaffolding in the zone of proximal development (Pathan et al., 2018).Language learning is the process of constructing knowledge and understanding in which learners face many challenges because Chinese is one of the hardest languages in the world.Consequently, teachers need to consider many factors, and learners will be able to learn a second language effectively if they understand the comprehensible input and the learner's affective filters are low enough (Lai & Wei, 2019).Chinese reading and writing skills are advanced skills for Thai learners, and Thai students often have problems with vocabulary and grammar because they have been accustomed to their mother tongue or first language.Mother tongue or first language disturbances are among the leading sources of second language learning errors.Contrastive analysis and error analysis is a good linguistic approach to studying the errors of learners.Thus, using the contrastive analysis hypothesis in second language learning is very useful for teachers and students (Khansir & Pakdel, 2019).
Learning Chinese as a second language is affected by a number of factors.Vocabulary and grammar knowledge are important factors in reading and writing a second language (Pae, 2019).Students with different vocabulary and grammar knowledge have clearly different Chinese reading and writing levels.As Zhou (2018) stated, vocabulary and grammar directly affect Chinese reading comprehension, positively correlated with writing skills (Rodríguez et al., 2017).In teaching and learning Chinese, teachers should help learners by using collaborative learning, which is a useful method for improving students' reading and writing skills (Gilakjani & Sabouri, 2016).At the same time, in order to be able to teach and learn efficiently, teachers' professional knowledge and teaching skills regarding their guidance roles should be regularly trained and improved (Özkan, 2022).In addition, teachers should encourage learners to strive for self-learning from daily activities in order to accumulate vocabulary and strengthen language sense.Using a second language in real life makes learning meaningful.It can be argued that social media plays a key role in teaching higher education in the 21 st century because it can meet the needs of learners (Ananga, 2020).Currently, there are various online resources and social media which can develop Chinese reading and writing skills effectively as well.As Adi Kasuma and Ai Lin Tan (2019) expressed that learners with good reading skills tend to experience self-improvement by using social media, which not only increases reading interest, it can also promote vocabulary, grammar, and writing skills.In addition, the northeastern region does not have a Chinese language environment like other parts of Thailand.However, the language environment in a classroom plays a very important role (Sheikh & Khan, 2019).Teachers should create a Chinese environment for students and offer opportunities to practice reading and writing skills for students.
For Chinese major students in the northeast of Thailand, the motivation for learning Chinese is instrumental motivation since Chinese has been a necessary communication tool in Thai society (Zhou, 2017).As Ahmadi (2017) stated, motivation is one of the key factors in helping learners try to understand the information and can help students be diligent in practicing reading and writing skills.Equally important, teachers should use various methods to motivate students to effectively promote their reading and writing skills (Teng & Zhang, 2018).Educational institutions should also organize various activities and competitions, allowing learners to apply their knowledge, build self-confidence (Zhou, 2017), and increase their motivation in learning (Phukanchana, 2018).Furthermore, attitude plays an important role in learning a second language.It is one of the main contributing factors to learning motivation (Liu, 2016).The most successful second language learners tend to have both a positive attitude and excellent aptitude at the same time (Zhou, 2017).A positive attitude has a positive impact on a self-learning, which also has a direct influence on the level of second language essay writing (Adaros, 2017).Besides, teachers should prepare content and activities that are relevant to students' interests.Finally, as a negative factor, anxiety negatively affects second language skills and indirectly affects self-efficacy (Zabihi, 2018).
Students have anxiety during Chinese reading because the number of words is insufficient, and the grammatical structure is difficult and complex (Sun & Luo, 2018).Moreover, teachers need to promote students' ability to use Chinese reading techniques such as guessing the meanings of characters according to the word formation rules and guessing contextual meanings by comprehension (Yang, 2010).Learners with writing anxiety, in addition to vocabulary and grammar problems, often have problems with not practicing writing and lack self-confidence (Yu, 2020).Another point is that teachers should encourage learners by using positive motivational guided words instead of criticism to promote their enthusiasm and confidence.

Conclusion and Recommendation
The results of this study proved that sociocultural theory, input hypothesis and affective-filler hypothesis of monitor theory, and contrastive analysis hypothesis were the appropriate theories and principles for improving Chinese reading and writing skills based on second language acquisition theory.In addition, vocabulary, grammar, language environment, attitude, motivation, and anxiety affected Chinese major students' reading and writing skills in northeast Thailand.Based on the results of the study, the following recommendations were proposed for teaching Chinese reading and writing skills to Chinese major students in northeast Thailand.
First, student-centered teaching should be adopted in the teaching and learning process, which requires learners to construct knowledge by themselves or learn with a peer, and the teacher has a role in giving advice when the students have problems.Furthermore, to better understand the students' learning situation, teachers should be able to analyze students' mistakes through the comparison between Chinese and Thai and guide students to strengthen their understanding and use of the target language from the comparison of the two languages.
Second, a model essay should be used for beginners, and the students should analyze the model essay and summarize the acquired knowledge.Through analysis and summarization, the original cognitive structure and knowledge structure could be reconstructed so that students can acquire writing knowledge, methods, and techniques through imitation.
Finally, the students' Chinese language sense should be strengthened.Input skills such as listening and reading could help learners develop a sense of language in an unconscious state, thereby improving output skills such as speaking and writing.Furthermore, the teacher should encourage the students and create opportunities for students to participate in various activities.In addition, Chinese learning habits should also be cultivated, such as perseverance, patience, and the courage to ask questions and express opinions.
Overall, in teaching and learning reading and writing skills in Chinese as a second language, teachers should create a relaxed learning environment, design a variety of interactive activities to help students transfer language knowledge into language skills, and encourage students to accumulate knowledge of Chinese vocabulary and grammar through online resources, and use Chinese in daily life and social media as much as possible.It is hoped that this research can be beneficial to learners of Chinese as a second language, teachers of teaching Chinese as a second language, especially teachers teaching Chinese reading and writing skills and related courses, and relevant personnel engaged in international Chinese education and research.

Table 1 .
Application of second language acquisition theory in second language skills teaching

Table 3 .
Components and factor loading of variablesFrom table 3, it could be explained that factors affecting Chinese major students' reading and writing skills in northeast Thailand consisted of 4 components: motivation, basic knowledge of Chinese, anxiety, difficulty, and feeling and opportunity.Motivation included interest in applying for a scholarship, expectations for living in China, and future career planning.Basic knowledge of Chinese included word formation in Chinese, vocabulary usage, vocabulary size, and grammar knowledge.Anxiety and difficulty included negative comments, exam anxiety, communication concerns, and difficulties in learning Chinese.Feeling and opportunity included Chinese usage in daily life, practicing in other subjects, feelings toward reading and writing in Chinese, and Chinese usage in social media.

Table 4 .
General information of the students interviewed

Table 5 .
General information of the lecturers interviewed

Table 6 .
Comparison of data analysis results from questionnaires, student interviewing form for students, and interviewing form for lecturers