“The term ‘blended learning’ first gained widespread currency in corporate training situations to describe the combination of teaching and learning approaches that included coaching, mentoring, online interactions, face-to-face classes, and on-job training” [1]. Research on definitions of blended learning can be classified into two types. One is to combine classroom teaching and online courses based on the percentage of online learning. In 2007, Smith and Kurthen distinguish related terms “web-enhanced”, “blended learning”, “hybrid learning” and “fully online learning” based on the percentages of online learning. They point out that blended learning refers to less than 45% of important online activities are used in face-to-face instruction [2]. And it is criticized for being oversimplified by only comparing time of online learning. In 2008, Watson presents that “blended learning defines a major segment of a continuum between fully online, at-a-distance courses, and fully face-to-face courses that use few or no Internet-based resources” [3]. And seven different categories of blended learning continuum are illustrated in detail.

The definition of blended learning also refers to blending face-to-face and online instruction, various pedagogical approaches and so on. In 2004, Garrison and Kanuka defines blended learning as “the thoughtful integration of classroom face-to-face learning experiences with online learning experiences” [4]. In 2006, Bonk and Graham advocates that “Blended learning systems combine face-to-face instruction with computer-mediated instruction” in The Handbook of Blended Learning Environments: Global Perspectives, Local Designs [5]. And different media and teaching methods differ in a continuum. Blended learning systems can be categorized in three ways: enabling approaches, enhancing approaches and transforming approaches. Besides, various models are raised to expatiate blended learning in which Community of Inquiry is the most influential one.

Compared with western scholars, domestic experts focus more on practical use of blended learning, such as influencing factors and effects than that on theoretical discussion. Next research on blended learning will be elaborated theoretically and practically.

In 2004, He Kekang, the first person who put forward blended learning after participating in The 7^th Global Chinese Conference of Computer in Education which marks the beginning of domestic research. He advocated that “blended learning aims to combine advantages of traditional teaching modes with that of E-learning (Digital Learning or Online Learning). Teachers should play a leading role in guiding, enlightening and monitoring in the whole teaching process while students, as main body of learning process, should fully reflect their initiative, enthusiasm and creativity” [6]. In 2004, Li Kedong and Zhao Jianhua illustrate blended learning “Principles and Application Models of Blended Learning”. It refers to an organic integration of face-to-face teaching and online learning in order to reduce the cost and improve teaching efficiency [7]. The concept of blended learning presented by He Kekang is used in this research.

Blended learning has been put into teaching practice which can be categorized into four types: different platforms, blended learning models, different guiding theories and influential factors. For example, Ling Qian and Ma Wulin verify the effectiveness of blended learning in “Research on Blended Learning of College English Based on Web2.0 Platform” [8]. Cao Peisheng published “Research on the Construction and Effect of ESP Blended Learning Mode Based on Flipped Classroom”. The study indicates that the blended ESP teaching mode in a flipped classroom can make courses more challenging, increase class participation, improve learning efficiency and practical ability [9].

In this part, blended learning models of English based on POA are discussed theoretically and practically.

Theoretically speaking, in 2021, Wang Lili and Zhang Xiaohui display specific methods and effective strategies of first-rate college course in “Construction of First-Class Blended College English Teaching with Production-Oriented Approach”. It includes output-driven teaching objectives, theme-centered teaching contents, FC-based teaching methods, multiple assessment as well as construction of moral teachers [10].

Practically speaking, blended learning models are constructed and put into teaching practice. For example, in 2019, Li Zuo put forward a blended learning mode guided by POA in “A Study on Blended Learning Model of English SPOC in Vocational Colleges”. And the results show that blended learning model integrates online and offline resources, which greatly makes the time and space of learning flexible and advances effective learning and language use [11].

According to the collected questionnaires, basic information about gender, English scores in China’s Entrance Examination for College and duration of English learning are analyzed. According to the data, nearly all students have learned English for about ten years except for two students from minority areas who never learn English. And their English scores in China’s Entrance Examination for College range from 25 to 98 out of 150. Some of them didn’t take the China’s Entrance Examination for College in June. Hence it can be found that although they have learned English for quite a long time, their English proficiency is generally poor and significantly different.

Questions 1 - 28 relates to students’ learning belief, learning style and learning autonomy respectively. In conclusion, students are not interested in English and weakly motivated to learn it. Although they have learned English for almost 10 years, their English proficiency is poor. Secondly, they prefer to listen to teachers' lectures and participate in class activities and group discussions. There are also some students who prefer to study alone. Thirdly, over half of the students can understand the teacher's requirement. Only one third of students make their own plans, monitor the use of strategies who have poor independent learning ability.

At the end of this experimental study, two students scored 0 - 60, 60 - 80 and 80 - 100 were respectively selected in EC for an interview. These students’ grades are relatively stable although they make progress in reading performance. Students scored 0 - 60 are considered as low achievers, students scored 60 - 80 are intermediate achievers and students scored 80 - 100 are regarded as high achievers. Then relevant records and analysis are made.

To sum up, all six students who participated in the interview unanimously expressed that the blended teaching model made the way of knowledge presentation more vivid and diversified. The class is more interesting, students’ enthusiasm in exploration and learning is enhanced, and their independent learning ability is improved.

For English high achievers, there is barely change in test scores whether it is blended teaching model or not. Students indicated that blended teaching model focuses more on cooperative learning and less knowledge is learned in class. That is to say, students with high English proficiency are not greatly affected by teaching model. However, their learning enthusiasm and independent learning ability are improved to a certain extent.

For English intermediate achievers, their English scores are drastically improved after the implementation of blended teaching model. According to the interview, students said that they become more interested in English reading. And they are more impressed about knowledge through their own study. Moreover, they are conscious to make their own plans.

For English low achievers, their test scores are relatively improved. However, they dare to speak up and are increasingly willing to take part in classroom activities. Besides, they are very happy with their progress.