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1.INTRODUCTIONThe experimental teaching is an important part in the Higher Education which aims to cultivate students with a wide range of abilities encompassing cognitive, practical and innovation abilities1. However, the traditional experiments are usually the verification, that is, students only need to verify some theory through existing experimental apparatus. Apparently, they can’t meet the requirements of talent training because their content is lack of stimulation and challenge to the development of students’ intelligence2,3. To this end, a number of colleges and universities set up a new type of experiments named comprehensive experiments as an essential part of practical teaching. The purpose of comprehensive experiments is to provide an open experimental condition and environment to allow students to design a system by their own. It is much better to develop the ability of students than through the verifying experiment. In this way, students’ in-depth understanding of knowledge, knowledge application ability, practical ability, troubleshooting and problem solving skills, and innovation ability can be greatly improved. Despite comprehensive experiments have been set up for several years in many colleges and universities, such as Zhejiang University, China University of Mining and Technology, University of Electronic Science and Technology of China and so on, there are still some problems existing in the comprehensive teaching as follows:
Confronted with the problems described above, it is urgent for us to take reform in the comprehensive experimental teaching to strength the students’ practical and innovation ability. In this paper, a new comprehensive experimental teaching mode is introduced while a photoelectric comprehensive experiment is taken as an example. 2.REFORM OF COMPREHENSIVE EXPERIMENTAL TEACHINGIn this section, a photoelectric comprehensive experiment is given as an example to introduce a new mode of comprehensive experiment teaching from three aspects: experimental design, teaching method and experimental evaluation. 2.1Experimental designing with practicability in project and comprehensiveness of knowledgeThe practicability in project and comprehensiveness of knowledge should be taken into account when we design a comprehensive experiment. The practical value of the experiment plays an important role to stimulate students’ interest. In addition, for the purpose of improving students’ ability of synthetical knowledge application, a good comprehensive experiment should involve knowledge of several professional courses. According to the above principles, a new photoelectric comprehensive experiment is designed. Rotational speed and direction measurement is widely used in the field of aviation, machine, precision machinery manufacturing, and so on4. Therefore, in the experiment, students are required to build a photoelectric detection system to detect the rotational speed, rotational direction and stop bit of a flywheel in real time. Rotational speed measurement is widely used in engineering. For example, we need to measure the speed of motor, alternator, spin axis of machine tools in real-time when they are rotating. Compared with mechanical measurements which have low accuracy, complex system and poor stability, the measurement based on photoelectric detection is steady, reliable, better in real-time and higher in accuracy. Generally, in the experiment, the speed, direction and stop bit are measured based on the electric signals transformed from the optical signals which are reflected by the reflective stripes on the flywheel. The experimental scheme is given in Figure 1. The light reflected by the reflective stripes on the flywheel is received and transformed into electric by a photoelectric detector, then the electric signal is amplified and reshaped into a square wave, based on which a single chip finally complete the measurement task and display the results in real-time. Obviously, this comprehensive experiment involves knowledge of light sources, photoelectric detectors, analog circuits, programs and so on. It provides a good opportunity for students to construct their comprehensive knowledge system. 2.2Student-centered experimental teaching methodStudies have shown that teacher-centered teaching may be the easiest teaching method, but it is not the best learning method. By traditional teacher-centered teaching, teachers introduce the experimental principle and method as detailed as possible, and students are expected to follow teachers’ instruction to do the experiment. In this case, though all students can complete the experiment, their practical ability can’t be improved and innovative thought can’t be stimulated. Comparing to the traditional teacher-centered teaching, student-centered teaching is a modern teaching method which treats students as the main body of teaching5. In our student-centered experimental teaching, we adopt the following methods:
2.3Process emphasized experimental evaluationThe experimental evaluation is used to evaluate students’ learning effects, what is more, it can be used to cultivate students into generalists6. For this purpose, a scientific and reasonable experimental evaluation is proposed to evaluate students’ ability and performance completely. The result of evaluation consists of scheme, operation, performance, report and presentation (as shown in Figure 2). To improve students’ innovative ability, the evaluation on scheme which account for 15% of the final grade pays attention to the feasibility and innovation of the scheme. At the beginning of the class, a scheme is introduced to students without the detailed design of each module, students can get an underlying score if they choose the scheme and complete the detailed design. Students who design a new feasible scheme can get a higher score. Table 1 gives the scoring rule. Table 1.The scoring rule of scheme.
To attach great importance to operation which reflects students’ ability of practice, the evaluation on operation takes up 40% of the final grade. The evaluation on operation takes independence, the ability of analyzing and solving problems and team spirit into consider. The scoring rule is given in Table 2. Table 2.The scoring rule of operation.
The performance of the system which takes up 20% of the final grade mainly aim to evaluate the accuracy and stability of the system. We give students an underlying score if the system only realize the basic function. For example, though the rational speed, direction and stop bit of the fly wheel can be measured, they depend on different programs. In other words, each program only implements one function. In this case, the system has a little practicability. Students will get a higher score if the system implements all functions depending on one program. In addition, the standardization of circuit connection is taken into account. As shown in Figure 3, the circuit connection in Figure 3(a) is more standardized than the one in Figure 3(b). Apparently, the stability of former is better than the latter. Each student is required to submit an experimental report. The report of the experiment takes up 10%. In addition to describing the scheme, students are encouraged to summarize the problems and their solutions in the experiment. It can help them to accumulate engineering experience. In order to improve students’ expression ability, at the end of the experiment, each team need to give a 5 minutes presentation and other teams can ask questions and communicate with each other. This part accounts for 15% in the calculation of the final grade. The scoring rule is given in Table 3. Table 3.The scoring rule of presentation.
3.CONCLUSIONTraditional experiment is attached to the theory teaching, and students only need to validate the content on the textbook with the detailed experimental instruction given by teachers. This kind of experiment results in the lack of autonomous learning motivation and creativity spirit of students. To address this issue, comprehensive experiments are set up in many colleges and universities. In this paper, a new teaching mode of comprehensive experiment is introduced while a photoelectric comprehensive experiment is given as an example. In the proposed teaching mode, the practicability in project and the comprehensiveness of knowledge is considered when an experiment is designed, and student-centered teaching method is adopt to take student as the subject in the classroom and encourage students to do the experiment independently. Besides, a scientific and reasonable experimental evaluation is proposed to test the students’ mastery theory knowledge, practical ability, innovative ability and expression ability comprehensively. Practice over a period of five years shows that, the new experimental teaching mode can effectively cultivate students’ comprehensive quality. REFERENCESHe, C., Lei, H., Wang, Q., and Gong, X.,
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