First, the design of teaching objectives
(A) the significance of designing teaching objectives
Teaching goal is the starting point and destination of teaching activities and the soul of classroom teaching. Therefore, the determination of teaching objectives is the first problem to be considered in teaching design. The significance of design teaching objectives is mainly manifested in the following aspects:
1. Teaching objectives are the basic basis for teachers to choose teaching content, use teaching methods, teaching strategies, teaching media and adjust teaching environment. Teaching objectives stipulate the direction, process and expected results of teaching activities, more specifically, they guide the direction of teaching activities. Only by knowing where to go can we choose the appropriate content and methods to achieve the expected goals. If there is no clear goal, teaching will lose its orientation and can only be carried out blindly. Therefore, the first step of design teaching is to determine a clear teaching goal.
2. Teaching objectives are the basic basis for evaluating teaching effect. Teaching goal has an important evaluation function, because it stipulates the expected results and quality requirements of teaching activities, so when testing and evaluating teaching effect, we must proceed from the goal and take the teaching goal as the basic evaluation scale. Missing or unclear teaching objectives will indeed bring difficulties to teaching evaluation. In this sense, clearly designed teaching objectives are also determined by the needs of teaching evaluation.
3. Teaching objectives are an important means of self-motivation, self-evaluation and self-adjustment. Because teaching objectives can provide students with a clear direction, so that students can clearly understand the specific goals to be achieved through learning, which can effectively stimulate students' internal motivation to learn, enhance their interest in learning, help students constantly adjust their learning methods according to the direction guided by the goals, actively overcome difficulties, and strive to achieve the predetermined learning goals.
From this point of view, teaching objectives play a variety of roles in teaching activities, such as pointing, evaluating and encouraging. Scientific and reasonable determination of specific teaching objectives in teaching design plays a very important role in ensuring the smooth progress of teaching activities.
(B) the steps of designing teaching objectives
1. Study the syllabus and analyze the contents of the textbook. Teaching syllabus is a guiding document about the teaching content and process of a subject, which stipulates the teaching purpose, teaching task, knowledge scope of teaching content, teaching time allocation and teaching method requirements of a subject, while teaching materials further enrich and concretize the teaching syllabus. The teaching goal is not arbitrary, and the design of the goal should be based on the careful analysis of the teaching syllabus and teaching materials. By studying the syllabus carefully and analyzing the textbooks, we can grasp the basic structure of the curriculum as a whole and clarify the knowledge system of the textbooks. On this basis, the teaching content of a unit is analyzed in detail to find out the basic concepts, principles and methods, so as to determine the key points and difficulties of teaching and lay the foundation for establishing teaching objectives.
2. Analyze students' current learning status. While fully studying the contents of the syllabus and textbooks, the formulation of teaching objectives should be based on students' characteristics and existing study preparations. Classroom teaching is to teach students what they don't know or don't know enough, and the knowledge and skills that students have mastered are the basis for further study, so the determination of teaching objectives can't be separated from students' existing readiness. The teaching goal should be the goal that students can achieve through hard work on the basis of existing study preparation. Therefore, students' original knowledge level, psychological development level and maturity, as well as students' attitudes, interests, hobbies and learning tendencies, all need to be carefully considered and analyzed when determining teaching objectives. In other words, teaching objectives must be related to students' existing learning preparation. For group teaching, students' general learning preparation and certain psychological characteristics are the main aspects to be considered when determining teaching goals, but at the same time, the design of goals should also fully consider the individual differences of students, especially the characteristics of children with extraordinary intelligence and learning disabilities, and formulate corresponding development goals so that each student can be fully developed.
3. Determine the classification of teaching objectives. After the completion of the above two basic tasks, the target design work has entered the substantive stage of putting forward the target and determining the target classification. From different angles and standards, we can classify teaching objectives in different ways. The main purpose of implementing goal classification is to improve the clarity and operability of goals in teaching, so that teachers can better guide and evaluate teaching according to goals. American scholar B.S. Bloom and his colleagues have made a systematic study on the classification of teaching objectives. They divide the teaching objectives into three areas: cognition, emotion and motor skills, and the objectives in each area are divided into several levels from low to high (see table 1 for specific classification). This classification method has great influence in the research field of target classification at present, and it has certain rationality, which can be used for reference by instructional designers when determining the classification of teaching objectives.
Bloom's teaching goal classification table and its application
2. The goal of love
3. The goal of motor skills
4. List the overall goals. After the classification of goals, designers can generally list various comprehensive goals, such as "improving students' reading ability" and "cultivating students' interest in music". The comprehensive goal reflects the overall requirements for teaching, but it is often general and difficult to observe and evaluate directly. Therefore, after listing the comprehensive goals, it must be further decomposed to make them operational and evaluable specific behavioral goals.
5. State specific behavioral goals. In other words, in terms of specific behaviors, list a series of teaching goals that can reflect specific learning results to illustrate each comprehensive goal. These specific behavioral goals can be directly observed and evaluated, and they can explain the degree to which students achieve their goals.
(C) the expression of teaching objectives
After the teaching goal is determined, how to express the teaching goal clearly, accurately and concretely becomes a key problem in the design of teaching goal. The traditional teaching objectives are often expressed mainly by teachers, using abstract and general words, such as "improving students' writing ability" and "cultivating students' good habits". The biggest drawback of this expression is that it is not clear enough, lacks maneuverability, and is difficult to measure and evaluate, and it is difficult to determine whether the teaching goal has really been achieved. Bloom's research on behavioral goals shows that the completion of teaching is the change of students' behavior. Whether it is cognitive, emotional or motor skills learning, it can finally be manifested in students' behavior. These behaviors can be observed and measured. Expressing teaching objectives in the form of behavioral objectives can effectively improve the guiding role of teaching objectives in teaching activities. Accordingly, a good expression of teaching objectives is to concretize the general objectives into observable and measurable behavioral objectives, explain what students can learn after teaching and to what extent, and explain the results that teachers expect students to change their behaviors, so as to help teachers grasp and evaluate the objectives in teaching.
Generally speaking, the expression of a well-defined behavioral goal should include the following four elements: ①.
1. Actor. Actors refer to learners, because behavioral goals describe students' behaviors, not teachers' behaviors. The goal of standardizing behavior should start with "students should ……", but it is not appropriate to write it as "teaching students …" or "cultivating students …", so the subject of behavior becomes a teacher, and the teacher's behavior is not what the teaching goal should describe. When expressing teaching goals, actors can omit writing, but designers should remember that appropriate goals are aimed at specific learners.
2. Behavior verbs. Behavioral verbs are used to describe the observable and measurable concrete behaviors formed by students, which are divided into fuzzy verbs and explicit verbs. Fuzzy verbs include: know, understand, appreciate, like, believe and so on. Clear verbs are: writing, reciting, arranging, choosing, recognizing, distinguishing, explaining, comparing and so on. In order to effectively improve the objectivity and operability of teaching objectives, designers should try to choose those behavioral verbs with clear meaning and easy observation when expressing behavioral objectives, and avoid using verbs with vague meaning and difficult observation such as "know" and "understand". Because the two words "know" and "understand" are terms to express the internal psychological process, which cannot be directly observed, the interpretation of these two words may be very different. For example, when teaching linear equations with one variable, if the goal is expressed as "making students understand linear equations with one variable", it is often difficult to clearly verify whether students understand linear equations with one variable at the end of teaching activities. However, if the goal is embodied as "being able to list a linear equation according to given conditions" and "being able to tell the meaning of terms such as linear equation, unknown number, root and solution equation", it will be easier to confirm whether the students have achieved the goal. The above table lists the behavioral verbs corresponding to various goals, which can be used for reference and choice by teachers and instructional designers.
3. Circumstances or conditions. Refers to the specific restrictions or scope that affect students' learning results, mainly explaining the situation that students complete the specified operations, such as "with reference books", "without reference materials", "according to pictures" and "reading the whole text". There are four situations: (1) whether manual and auxiliary means are used or not. Mark ... on a blank map of the world. (2) provide information and tips. For example, give a list of historical figures. (3) Whether tools and special equipment are used. For example, without a calculator. (4) the completion of the behavior. For example, in class discussion, the main points of the statement.
4. Performance level or standard. Refers to the minimum performance level of students to achieve their goals, which is used to evaluate the degree of academic performance or learning achievements. For example, "at least 15 of the 20 questions are answered correctly", "90% correct", "completely correct" and "completed in one minute". Standard descriptions can be quantitative or qualitative, or both. General behavior standards are divided into three categories: (1) time limit for completing behavior. Like three minutes to solve the problem. (2) Accuracy, that is, the percentage or times of correct operation and operation. For example, the correct answer rate is 90%. (3) the characteristics of success. For example, answer to three decimal places. Examples of complete behavioral goals are as follows:
In short, the correct expression of teaching objectives is a very important link in the design of teaching objectives. The above expressions provide a general model for teachers and instructional designers to refer to. The teaching objectives expressed in this way are clear, observable and measurable, which is conducive to guiding and evaluating teaching. However, due to the complexity and diversity of actual teaching, it is not necessary to strictly apply this method when drafting teaching objectives. Because some psychological processes as goals are difficult to be described by explicit actions, for example, only a few goals in the emotional field can be described by observable and measurable terms, and some goals cannot be described by behavioral verbs. In this case, teachers should flexibly express teaching objectives according to the needs of specific teaching tasks and teaching situations, and can use some qualitative terms and general descriptions to state teaching objectives instead of mechanically applying some specific behavioral verbs to avoid common sense mistakes.
Second, according to the actual development level of students to determine the starting point of teaching design
Fully understanding the actual development level of students and accurately grasping the starting point of teaching are important contents of teaching design. The actual development level of students mainly refers to their existing knowledge preparation, ability level, physical and mental maturity and learning motivation. Students' existing knowledge and ability level and learning preparation are the basis of teachers' teaching. Only when teaching is based on students' actual development level can the communication between teaching and learning become possible.
In the process of teaching design, the basic significance of accurately grasping the actual development level of students lies in: (1) helps teachers to determine the appropriate teaching starting point. The starting point of teaching is always based on the existing development level of students. Too high or too low a starting point can not stimulate students' learning motivation and promote their normal development. Therefore, a comprehensive understanding of students and an accurate grasp of their current development level are of great significance for teachers to correctly determine teaching objectives, choose teaching contents, design teaching processes and ensure the smooth development of teaching activities at a good starting point. (2) It is helpful for teachers to choose appropriate teaching methods and media, adjust various environmental factors, provide students with background knowledge, create a good learning environment, and promote the internal relationship between starting behavior and new learning. (3) It is helpful for teachers to identify individual differences of learners, so as to teach students in accordance with their aptitude and make all students develop to a corresponding degree.
Determine the actual development level of students can be carried out from the following three aspects:
1. Cognitive factors. It mainly includes students' existing intellectual development level, learning skills, knowledge reserve, cognitive structure and cognitive style (different learning styles).
2. Non-cognitive factors. It mainly includes students' general physiological development level and maturity, students' learning motivation state such as learning interest, attitude, need, intention and emotional state.
3. Social factors. It mainly includes the cultural background and professional background of students' families, the social communication and mutual relationship between students, and the interpersonal relationship between teachers and students.
On the basis of fully understanding the above aspects of students, teachers and instructional designers need to pay special attention to and carefully analyze students' existing knowledge preparation and learning motivation, because these two factors are the main aspects that constitute students' realistic learning level.
The study of learning psychology shows that students' existing knowledge preparation, especially the cognitive structure formed on the basis of existing knowledge preparation, is an important factor affecting students' new learning or subsequent learning. Cognitive structure in a broad sense refers to the whole content and organization of learners' original ideas. In a narrow sense, cognitive structure refers to the original concept, content and organization that learners are suitable for assimilating new knowledge when learning a certain subject or unit. Contemporary cognitive theory, especially American psychologist Ausubel's meaningful speech learning theory, especially emphasizes the significance of cognitive structure in students' learning. According to these theories, all the new and meaningful learning conducted by students is based on the original learning, and it is a process in which new knowledge is substantially related to the knowledge and experience in students' original cognitive structure. In the actual learning process, whether the new knowledge and the old knowledge can have this substantial connection depends on the basic characteristics of students' cognitive structure, such as the level of abstraction and the stability of the original concepts, and on whether teachers accurately design the starting level of teaching on the basis of clearly understanding the students' cognitive structure, and correctly grasp the structure, internal relations and order of teaching materials. Therefore, before the start of new teaching activities, teachers must carefully understand the students' existing knowledge preparation and whether students have the conditions to learn new knowledge. For example, to teach students "binary addition", it is necessary to know whether students have the basic knowledge and concepts of accepting assimilation in their knowledge structure. If they can't add a digit, they can't be taught binary addition.
The theory of "advanced organizer" put forward by Ausubel is of great significance for how to accurately design the starting point of teaching, so as to help students quickly and effectively establish the connection between old and new knowledge and promote the completion of learning tasks. The so-called "advance organizer" is actually the guiding or background knowledge materials presented to learners in common languages that learners can understand before the formal study begins. The main function of "advance organizer" is to provide a suitable starting point for teaching and act as a bridge between old and new knowledge. "Advance Organizer" is best used in two situations. In one case, if there is no clear distinction between old and new knowledge, students will easily get confused in the meaning of new knowledge, so teachers can design and present a material at the beginning of teaching to let students compare the similarities and differences between old and new knowledge, so as to improve the distinction between old and new knowledge and ensure the smooth learning of new knowledge. On the other hand, when students are faced with a new learning task, if there is no suitable upper concept in their cognitive structure to assimilate new knowledge, teachers should first design and present an organizer with higher tolerance and generalization level than the new materials to be learned, so that students can learn this organizer first, so as to obtain a cognitive framework that can assimilate new knowledge and complete new learning tasks. However, it is still a prerequisite to accurately understand students' existing knowledge preparation whether they can design advanced organizers that meet the actual needs and find suitable teaching breakthrough points.
There are many ways to understand, diagnose and identify students' existing knowledge preparation and learning motivation. According to the actual needs of teaching and the specific requirements of teaching content, teachers can choose various methods to get to know students, such as questionnaire survey, conversation, observation, classroom questioning, homework, tests and examinations. As long as every teacher can consciously observe students in many ways and understand them in daily teaching, in the long run, all kinds of situations of students will be clear. In this way, on the basis of fully understanding the students' learning situation, reasonably designing the teaching starting point and arranging the teaching process can continuously improve the teaching level and effectively ensure the teaching quality.
Third, the teaching content design
Teaching content design is an important part of teaching design. The design process of teaching content is also a process in which teachers carefully analyze teaching materials, reasonably select and organize teaching content, and reasonably arrange the expression or presentation of teaching content. The teaching content is embodied in the textbook. Because the arrangement and compilation of teaching materials are limited by written forms and other factors, the knowledge content and structure it presents must be re-selected, reorganized and re-processed by teachers to meet the actual needs of teaching, from dead materials to living knowledge, and finally effectively internalized into knowledge mastered by students. Therefore, teachers must pay attention to the design of teaching content. Whether the teaching content has been carefully designed or not, the actual teaching effect is very different.
Relevant research shows that it is an important aspect of teaching content design to identify different types of knowledge and design teaching according to the characteristics of different types of knowledge. From the perspective of instructional design, knowledge is generally divided into the following three categories: ①.
(A) Instructional design based on declarative knowledge characteristics
Declarative knowledge is mainly about what the world is. This knowledge can be divided into three forms:
1. Knowledge about names or symbols of things. Learning this kind of knowledge needs to remember the symbols of things and the individual things represented by symbols, and get an isolated message. For example, the study of foreign language words is this kind of knowledge.
2. Simple propositional or factual knowledge. This kind of knowledge is acquired by studying the single proposition that "the capital of China is Beijing" and "a triangle has three sides".
3. Combinatorial knowledge of meaningful propositions, that is, organized verbal information. This knowledge is needed to state the reasons for the failure of the Taiping Heavenly Kingdom.
Teaching design according to the characteristics of declarative knowledge is beneficial to the storage, extraction and recall of knowledge. The teaching goal of this teaching design is mainly to cultivate students' ability to recall knowledge. Teachers can check whether students have developed this ability by asking them to state orally or in writing what they have learned in classroom teaching. Therefore, in the teaching design of declarative knowledge, teachers should focus on how to effectively help students understand and master this kind of knowledge, and pay attention to students' acquisition of symbols or meanings in declarative knowledge. To do this, teachers should solve the following problems in the specific design process: 1. Find out the combination of new knowledge and original related knowledge, clarify the relationship between them, and help students absorb and assimilate new knowledge effectively on the basis of understanding. 2. Make a careful analysis of students' learning preparation. Besides the general learning situation of students, we should also make an in-depth analysis of students' existing knowledge preparation, knowledge structure, learning motivation and learning habits. 3. Appropriate introduction of teaching media, such as the use of teaching AIDS and learning tools, changes in the presentation means of teaching materials, etc.
(B) Teaching design according to the characteristics of procedural knowledge
Procedural knowledge is about "how to do it". For example, if students are required to calculate the area of a circle according to a given radius, classify a bunch of mixed vegetables and fruits one by one, and modify the ill sentences according to grammar, they can complete these tasks correctly and smoothly, that is, they can obtain the corresponding procedural knowledge.
As can be seen from the above, procedural knowledge mainly involves the application of concepts and rules, that is, classifying things and performing a series of operations and operations. In teaching practice, how to transform the propositional knowledge such as principles, laws and rules stored in the mind into skills, and realize the transformation from static to dynamic, from stored knowledge to information, from slow reproduction of knowledge to automatic activation, so as to realize the development of learning, is a key issue in teaching design. Therefore, the teaching goal of procedural knowledge teaching design is mainly to help students form the ability to solve problems by using concepts, rules and principles. The behavioral index to test this ability is whether students can use the concepts and rules they have learned to perform operations smoothly. In order to achieve this goal, the teaching of procedural knowledge should have sufficient practical design. When designing conceptual exercises, we should pay attention to the full use of positive and negative examples. Giving positive examples is helpful to generalization and migration, but it may also lead to generalization. Putting forward counterexamples helps to distinguish and make concepts accurate. While learning and mastering the rules, it should be supplemented by some exercises to guide students to apply the newly learned rules to the problem-solving situation in time, so that they can respond immediately when they see the right conditions. For the teaching of a long list of procedural knowledge, we should also consider the dispersion and concentration of practice time and the relationship between part and whole. Practice local skills first, and then practice the whole. In short, when designing this kind of knowledge, teachers should plan teaching and practice time reasonably, so that the mastery of rules and concepts and the formation of problem-solving skills can be effectively guaranteed in classroom teaching.
(C) Teaching design according to the characteristics of strategic knowledge
Strategic knowledge is also the knowledge of how to answer. The main difference between it and procedural knowledge is that the object it deals with is the individual's own cognitive activities, and it is the knowledge that the individual regulates his own cognitive activities. For example, under the condition of declarative knowledge, some students are flexible when facing new learning tasks, and some students are slow to respond and have poor adaptability. An important reason for this learning difference is whether students have mastered certain strategic knowledge.
Generally speaking, strategic knowledge is divided into two levels: the lower level is the strategic knowledge of general learning activities, such as strategies to control and adjust attention, memory strategies and extraction strategies; The higher level is the knowledge of creative thinking strategies, which often varies with time, people and content. It is a reasoning process and difficult to program, and there is no clear classification at present. According to the characteristics of strategic knowledge, teaching design needs to solve three difficult problems: (1) textbook problem. Traditional textbooks do not take the training of cognitive strategies as an important goal, and there is a lack of corresponding content in the textbooks. (2) the problem of teachers. Strategic activity is an internal thinking activity. How to make this hidden activity be imitated by students, the key is that teachers should be good at describing internal thinking and let students imagine. At present, many teachers lack the knowledge and training of strategy teaching, and they don't know how to explain strategies to students. Therefore, teachers should strengthen the study and training of strategy teaching knowledge in order to design strategy knowledge well. (3) Students' problems. Students' cognitive strategies restrict the teaching of strategic knowledge, so paying attention to the training of students' cognitive strategies is an important part of teaching design. For example, controlling students' attention by asking questions gradually changes from external control to self-control; Teach students how to take notes when listening to lectures and reading books; It can also teach students how to organize and process knowledge, promote memory and facilitate recall.
In short, to do a good job in the teaching design of strategy knowledge, teachers should first learn and master the knowledge about learning strategies and cognitive strategies, strengthen the training of strategy teaching, and at the same time pay attention to excavating the content of strategy knowledge in teaching materials, and then carry out targeted teaching design according to the characteristics of strategy knowledge and students' learning.
Fourth, the design of teaching time.
(A) the significance of designing teaching time
Time is a concept of physics, as well as psychology and pedagogy. From the psychological point of view, time is the decisive factor in students' learning process. From the perspective of pedagogy, time is an important educational resource. Teaching activities in schools are always carried out within a certain period of time, and teaching time is an important factor affecting teaching activities. To some extent, controlling and changing teaching time means controlling and changing teaching activities. Therefore, in teaching practice, it is an important content of teaching design to understand and study teaching time, and to allocate and control teaching time reasonably according to teaching needs.
For a long time, many researchers have made special research on teaching time. Carol's research shows that time is the central variable of teaching, and time is closely related to students' learning activities and academic performance. In the actual learning process, the time required for everyone to learn a unit is different, and the time actually spent by everyone learning a unit is also different. The function of the ratio of the two determines the degree of learning, and the relationship can be expressed by the following formula:
Carlo theory reveals the internal relationship between learning efficiency and learning time, indicating that learning time is an important factor affecting students' learning activities. In addition, Harnisch Feger&Wiley's research shows that there is a linear correlation between teaching time and teaching results, and students' academic performance depends on the time when students actively participate in learning and the existing learning preparation state. In other words, the more time spent on teaching, the more time students take the initiative to participate in learning, and the higher their academic performance and teaching effect, the better.
Lorin W. Anderson and Cahuette believe that the relationship between time and teaching effect is not just a straight line, but a dynamic correlation. They put forward the time-based teaching theory of "timing" respectively, arguing that the design of teaching time should not only pay attention to the total amount of teaching time, but also pay attention to the dynamic relationship between timeliness, timeliness and timeliness and teaching efficiency. Anderson summed up five concepts of "timeliness": ① Development opportunity. It refers to whether students can be given learning opportunities according to their physical and mental development stages, so as not to learn too early or too late and get twice the result with half the effort. Second, the timely starting point behavior (entry—-behavior timing). It refers to whether it is the right time for students to have a specific starting point knowledge, skills and attitude when they start learning a specific learning unit. Third, timely (instantaneous timing). It refers to grasping the opportunity at the most appropriate time and guiding students to obtain the best learning effect in the most appropriate way. Fourth, timing is like keeping pace. Refers to the ability to teach a series of learning units one by one at an appropriate speed and at an appropriate time. Fifth, as a management opportunity. It refers to whether the teacher guides or counsels the right students at the right time. On this basis, they believe that adding a unit of teaching time, no matter which learning unit is distributed, the learning effect is the same. How to organize and use the same time plays a decisive role in the teaching effect. In other words, the effect of teachers' teaching and students' learning depends not only on how much time they spend, but also on when and how they use it. Therefore, in the design of teaching time, it is of great significance to fully understand the above five time concepts and rationally allocate and use teaching time for improving teaching efficiency.
(B) Design the teaching time dimension
In the actual design process, teachers must comprehensively consider various factors, grasp the exact meaning of teaching time from different dimensions, and understand the time benefit of teaching from different aspects, so as to make the design of teaching time more scientific and reasonable and meet the actual needs of teaching. The following concepts must be understood and mastered by teachers when designing teaching time, which determine the time benefit of teaching from different dimensions.
1. Nominal learning volume. That is, the total amount of study time required by students, which is embodied in the total hours of school each year. In China's primary and secondary schools, this amount of time is stipulated by the state, so there is little difference in the total number of hours between schools each year. This amount of time is designed for students as a whole, which is different for each individual student, so it is necessary to examine the actual effective learning amount of individual students.
2. Actual learning volume. Refers to the amount of effective study time actually accepted by each student. In the actual teaching process, due to the influence of students' lateness, truancy, absence of teachers and other factors (such as the interruption of teaching caused by random activities organized by the school, the interference to teaching), the effective learning amount actually accepted by each student and students from different schools is not exactly the same. Relevant research shows that students' attendance rate is directly proportional to their academic performance, and their academic performance is affected by comprehensive factors such as attendance days, unreasonable absence and lateness. Therefore, ensuring each student's actual learning volume is an important aspect of teaching time design and control.
3. Unit class hours. Refers to the amount of learning time that students gain by learning a unit or a specific content in class. In actual teaching, teachers have great differences in the time allocation of various course contents (such as reading, thinking, practicing, discussing and testing activities). The research shows that the relationship between this difference and students' grades is also very complicated, some are positively related and some are negatively related. Therefore, when determining the allocation of classroom teaching time, teachers should fully consider the content of teaching materials, students' learning characteristics and other factors, and must not act according to personal interests and habits.