2.1.1 Big Idea
Big idea can go back to Bruner’s discussion of the Process of Education. Bruner points out that there is a basic structure of things and the learners’ task is to learn that basic structure and how things are related to other things through some basic structure. He believes that the core of the educational process is the continuous expansion and deepening of knowledge with fundamental ideas (Bruner, 1960).This shows that big idea plays a vital role in students’ understanding of the world. Then, big idea has been defined from many angles by different scholars. To sum up, scholars at home and abroad have roughly formed four basic views on the connotation of big idea:
(1) Superior concept
It is considered that big idea is a concept at a higher level, which can be connected with the lower concept and has universal explanatory power in a larger scope. The representative figure is Wang Qiang. Wang Qiang et al. (2020) believes that big idea can be understood as the superior concept that is integrated or refined from scattered concepts, which makes meaningful connections between the limited and deep important concepts to form a coherent whole of the discipline, so that the discipline is no longer presented as fragmented concepts, principles and processes. Meanwhile, big idea shows important meaning and value in English teaching design and it also makes students’ learning more tightly linked, pointing to the depth of learning.
2.2 Previous Research on Big Idea and Integrated Unit Teaching at Home and Abroad
In this part, the previous studies will be introduced. Learning about the previous research results can provide a strong argument for the research of this thesis.
2.2.1 Previous Research on Big Idea at Home and Abroad
(1) Previous research on big idea abroad
Big idea was first used in the field of science and was first introduced by Bruner, a leading American educational psychologist in the 1960s. Bruner points out that there is a basic structure of things and the learners’ task is to learn that basic structure and how things are related to other things through some basic structure. He believes that the core of the educational process is the continuous expansion and deepening of knowledge with fundamental ideas (Bruner, 1960).
On the theoretical level, the research mainly includes the connotation, construction and significance of the big idea. Harlen (2016) proposes that big idea is a concept that can be used to explain and predict a large range of natural phenomena. Wiggins and Mctighe (2005) take the teaching theory of Reverse design as the core in their book Understand by Design and construct understanding framework. The main contents are divided into three levels: basic knowledge to be understood, important teaching contents to be mastered, big ideas and core teaching tasks. Among them, the big idea is the focus of learning and is in the center of the curriculum. Big idea is more like a holistic teaching tool, not limited to a subject concept. It can help students improve their learning thinking, connect scattered knowledge and enable students to apply and transfer knowledge on the basis of understanding knowledge. Erickson (1995) talks about the significance of big idea and points out that big idea has great transferability value and can be applied to many other vertical intra-disciplinary situations and horizontal inter-disciplinary situations as well as new situations outside of school. According to the Next Generation Science Standards: For States, by States released in April 2013, each of its contents contains three dimensions: the core concept of the discipline, the practice of science and engineering, and the interdisciplinary concept. It emphasizes that in basic education, students continue to learn several interdisciplinary concepts in each topic and core concepts in each subject area, and integrate them with engineering practice (NGSS, 2013).According
