1. Research background

In 2014, the Ministry of Education developed and issued "On Deepening Curriculum Reform in an All-Round Way and Implementing the Principle of Morality"

"The Ministry of Education will organize research to put forward a core quality system for the development of students at all levels of study, and to identify the necessary qualities and key abilities that students should possess to meet the needs of life-long development and social development." [1] On the basis of training talents, the new curriculum standard has started a comprehensive adjustment and reform. In this kind of adjustment and change, a new term "historical key ability" was put forward. With the development of education in recent years, the Ministry of Education has proposed in the "Introduction to General Senior High School History Textbooks" in 2019 that "the requirements for the cultivation of the key competences of the history should be fully implemented" [2]. As the general goal of the history curriculum, the key competences of the history is the concrete embodiment of the students' development of the key competences in the history curriculum and plays a particularly important role in the history [3]. However, in the current middle school history teaching, there is a widespread phenomenon of "memorizing more and understanding less". This mechanical teaching mode restricts the students' cognitive ability to a great extent, which makes students lack the attitude towards history. Students tend to use mechanical learning to achieve the effect of coping with exams, but pay little attention to the key competences and value connotation of history itself. With the continuous development of education, the demand for the quality education ability of the subject is constantly improving, and the core quality of history subject is beginning to be valued. In recent years, with the development of the key competences of the history, many scholars have done research on it, and explained the connotation and educational methods of the key competences of the history from the perspectives of value orientation, situational problems and historical thinking. They also summarized the dimensions and development of the key competences of the history. However, there is no complete overview of the whole process of the key competences of the history itself, and the description of all aspects of the whole is scattered, without integrating its connotation, value and deeper global cultivation path. The purpose of this paper is to comprehensively sort out the connotation of the key competences of middle school history, and to explore the reasons and values for it to become the core of the history. By reviewing all aspects of the key competences of the history, the teachers can have a deeper understanding of the key competences of the history in the middle school, which is conducive to get rid of the existing mechanical teaching problems, and also plays a certain reference role for other scholars to study the key competences of the history.

2. The connotation of the key competences of middle school history

The 2017 edition of senior high school history curriculum standard clearly defines the key competences of the history: "the key competences of the discipline is the concentrated expression of the value of discipline education, and is the correct value concept, necessary character and key ability that students gradually form through discipline learning." In many previous studies by scholars, Xu Lan believed that the key competences of the history literacy is the key ability, the necessary character and the value concept that the students gradually form in the process of learning the history knowledge and show when solving the problems in the real situation. It is the general and professional expression and concentrated expression of the educational value of the history literacy [4]. Lei Ming, Zhu Liming and Wu Liza think that the key competences of history is the relatively stable and necessary thinking quality and key ability that students cultivate in the learning process of history, which reflects the characteristics of history. It is the organic composition and comprehensive reflection of historical knowledge, ability methods and emotional values [5]. They all embody the value, ability and quality of the key competences of the history literacy. Therefore, this study believes that the core quality of history literacy is the core quality of emotion, knowledge, ability and other aspects condensed by students in the process of history learning, and is the value embodiment of the ability to understand and comprehend history literacy. As the focus of history, it contains five aspects: historical materialism, concept of time and space, historical evidence, historical explanation and feelings of family and country [6].

Historical materialism is generally regarded as historical materialism, "a philosophical theory of the general law of human social development, and an important component of Marxist philosophy." In history teaching, historical materialism is suitable for revealing the grand and universal laws of history, has a strong explanatory power to the macro history, and is conducive to the promotion of situational teaching [7]. The concept of time and space is an organic combination of the concept of time and the concept of space, and is the basis for understanding and understanding history [8]. Under the context of the concept of space-time, time series and spatial elements construct the historical framework and the relationship between event. Therefore, in the process of exploring history, it is often necessary to combine the concept of space and put historical events in an accurate space-time framework in order to fully understand the historical picture. As an important proof of textual research on historical correctness, historical materials have always been highly valued. Empirical evidence refers to the attitude and method of discriminating the obtained historical data and trying to reproduce the historical truth with credible historical data. It is not only the link to realize the key competences of the history literacy, but also the most distinctive "methodology" of the history literacy, and it is also an important embodiment of the "obtaining and interpreting information, demonstrating and discussing problems" required by the goal of the college entrance examination ability [9]. Interpretation is "an explanation of the essential characteristics of a thing or the connotation and extension of a concept." Therefore, starting from the essence of interpretation, historical interpretation is to explain and summarize the laws behind historical events. Such objective interpretation of history often helps people to better understand history. The feeling of family and country is the humanistic pursuit for studying and exploring history, which reflects the feelings for the country's prosperity and people's happiness, as well as a high sense of identity, belonging, responsibility and mission to the country [10]. As one of the important conditions to cultivate the key competences of the history, this kind of feelings of home and country can often improve people's enthusiasm for exploring their own national history, help people understand the significance and value of history, and thus cultivate the key competences of the history.

3. The value of key competences in history

As the core of history literacy, history key competences plays an extremely important guiding role in history, whether in teaching or in the whole history system. This kind of guidance is largely reflected in the value level. The value of the so-called key competences of the history literacy is also called the historical value, which refers to the value orientation that has been tested and tested from the noble pursuit of seeking truth, understanding, morality, speech and meritorious service in historical records and historical research [11].

3.1. Promote students to shape the feelings of family and country and the values of life

For the students, the key competences of the history has shaped their overall understanding of the history. In the process of learning history, the students can not only cultivate their sense of identity of history through the core accomplishment of the history, but also cultivate their feelings of home and the country. This historical sentiment helps students to understand history from a humanistic perspective, think about the historical significance from emotional, political and cultural aspects, and think about the changes of historical dynasties on a warm level, thus forming a nation-to-nation culture. This enables students to constantly explore the truth of the universe and human happiness with the spirit of "good history" and the fine tradition of "expressing their feelings directly", learn from great historical figures in the process of historical development, and absorb beneficial spiritual wealth [12].

3.2. Promote the combination of teachers' curriculum teaching with historical value and depth

As far as curriculum teaching is concerned, the introduction of the key competences of history is beneficial for teachers to have a brand-new understanding of history teaching preparation. Teachers can integrate and disassemble book knowledge through the five levels of the key competences of history, classify the knowledge of middle school history in detail, continuously consolidate the development of history teaching through the five levels of the key competences of history, explain history from the perspective of cultivating the key competences of history, teach history knowledge more intuitively, and combine history knowledge with historical value to further improve students' key competences of history. This kind of teaching helps to pave the way for students to have feelings and understanding of history from the beginning.

3.3. Promote the improvement of the evaluation system of relevant aspects of history literacy

The key competences of history makes the history teaching evaluation system related to history more complete. As an important evaluation standard, historical key competences can be used to measure whether the important links such as historical knowledge, classroom teaching, curriculum system and so on have the connotation and value of historical key competences. For students, the key competences of history can be used to evaluate whether they are familiar with history. For teachers, the key competences of history can be used to evaluate whether the teaching is up to standard, and for the curriculum system, the key competences of history can be used to evaluate whether the system is complete. The improvement of the evaluation system is conducive to the progress of history.

4. The way to cultivate the key competences of history

4.1. The state carries out relevant macro-adjustments to cultivate the key competences of the history in all provinces and cities

Starting from the primitive society, the origin and development of human beings will be revealed through history. Whether it is Chinese history or world history, the purpose of learning is to make students do not forget their initiative mind, remember history, learn from history and contribute to the development of the motherland and the progress of the world [13]. With the history subject beginning to be re-valued by people, a new term "key competences" of history subject has been put forward in recent years. However, it is still difficult for the key competences of history to be popularized and implemented in all regions, which requires macro-control by the state. First of all, the state can promulgate regulations on the key competences of the history and implement the cultivation of the key competences of the history in various provinces and cities through the form of laws. Secondly, the state can make relevant adjustments to the standards for students to study history, bringing the key competences of history into the standards so that students can understand the importance of the key competences of history. Finally, in the face of the news blockade of the people, the state can assign the propaganda task to the regional governments, and let the people know the key competences of the history and the importance of the key competences of the history through the propaganda and announcements of the provincial and municipal governments.

4.2. Teachers from their own emotional breakthrough, change the innovative teaching model

Teachers have always been disseminators of subject knowledge, which has a very important impact on the development of teaching for students. However, the identity of a teacher cannot be fixed all the time. From another perspective, what we have to do is "no longer just look for the professional attributes of history teachers from history education itself, but need to find out the irreplaceability of history teachers' profession by comparing with other professions."[14] The uniqueness carried by history teachers is the key point of their continuous exploration on the history road. As a teacher, in the process of junior high school history teaching, a certain breakthrough needs to be made in emotion. The charm of language emotion is always the focus of the classroom. Previous teachers had been clinging to the explanation of the textbook itself and neglected the emotional mobilization of themselves. Therefore, in addition to explaining knowledge in the classroom, teachers need to bring their emotions into the classroom. They can read the knowledge emotionally or remind students to bring themselves into the situation when a certain historical event occurs, feel the historical atmosphere at that time, and achieve the emotional commonality between teachers and students. This is more helpful to the degree of knowledge absorption between teaching and students.

Besides, in the teaching mode, we can adopt a new mode of creating problem situations. Problem situations refers to the spatial learning environment in which a series of analysis, understanding, induction and other methods are used to achieve learning objectives under the guidance of specific objectives, namely the so-called problem situations [15]. Teachers need to create such historical problem situations, such as asking questions related to topics such as the background and psychological activities of characters, to create problem situations for students, so that students can understand the nature of history by exploring these problems, stimulate students' interaction and interest, and gradually promote the cultivation of historical key competences by guiding students' inquiry.

4.3. Students need to put in their own understanding and cognition to strengthen the learning cooperation among groups

As the most intuitive object to receive historical knowledge, students cannot regard history as a subject only suitable for examination. The famous saying "all history is contemporary history" mainly shows that any history that has been interpreted or restated by contemporary people inevitably permeates contemporary people's thoughts, emotions and values [16]. In daily life, when reading or studying history, students should start from their own point of view. For example, when they encounter a historical event, they should think about why it happened, what are the direct and fundamental reasons, and what are the positive and negative effects. If they are faced with historical events, what are the key points they will think. At the same time, in the process of learning history, students can realize the development of values, attitudes, skills, knowledge, etc., and effectively cultivate students' practical ability, innovative ability and exploration spirit through cooperative inquiry and activities such as division of labor, cooperation, exchange and discussion [17]. Students should start a group discussion on a historical topic or a topic proposed by the teacher. Each person can be responsible for a section, which can be a collection of background or a collection of process. Then they can exchange views or attitudes towards this historical event through a group discussion. On this basis, it can be extended appropriately, such as the Opium War, which can be associated with when the foreign trade with China began, whether Britain had the idea of invading China to open up China's trading market before the Opium War, and so on. Through the historical events of one point, it can be connected with other points to conduct extended learning. This exploration can enable students to share knowledge points with each other and promote the cultivation of historical key competences.

5. Summary and prospect

The core quality of history is the core quality of emotion, knowledge, ability, etc. Condensed by students in the process of learning history, which occupies an important position in middle school history. As the core of middle school history, cultivating the core quality of history can not only promote the cultivation of people's feelings of family and country, but also help people to establish a correct outlook on life and values, better understand history and understand the emotion contained in history. These provide an important reference for how to further deepen the curriculum materials in the future. This study expounds the connotation, value and training path of middle school historical key competences, but the historical evaluation system needs to be constantly improved in the future, which can be verified by constructing and improving the historical key competences evaluation system. At the same time, it is also an important direction in the future to make an empirical study on the influencing factors of historical key competences by investigating the status quo of students' historical key competences in different regions.