Keywords: variant exercise students' main body
In the whole teaching process, the evaluation of test papers seems to be a link that teachers easily ignore. Teachers are fully prepared for new lessons and review lessons, and the teaching plan will be written more completely. The lecture and marking of the test paper is often to do the test paper again and take a test paper with standard answers to class. As for students' feedback on a certain stage of learning, teachers can make up for some "omissions" and "deficiencies" in teaching during this period through a lecture and evaluation. It doesn't matter if students are "wrong", it depends on the evaluation quality of "no longer wrong" after class.
The key to do a good job in class evaluation is the preparation before class and the reform of classroom form.
First, preparation before class
The preparation of lessons in the early stage of lectures and evaluation includes data statistics and exercise selection.
Before commenting, you should make relevant statistics, including the statistics of test scores and the scoring rate of each question. Only by comprehensively grasping the data can we fully grasp the overall situation of students and put forward targeted opinions. For students with the highest grades and higher grades than college students, they should be read by name, especially those with poor foundation. Teachers should carefully capture their highlights from the test papers. The novel ideas and insights found in the marking process should be recommended to the whole class; In short, everything is to improve students' interest in learning. Of course, don't wear a hat too high, which will make students feel arrogant, so the scale of praise will vary from person to person; For those who are behind in their grades, we should be alert and motivated, so that they have a sense of crisis and are full of hope for future study. Don't make students feel inferior, make them uninterested in mathematics and give up on themselves. Therefore, accurate statistics in the early stage is the basis for doing a good job in lectures and evaluations.
The selection of evaluation topics should also be fully detailed. After mastering the scoring rate of each question, choose the questions with lower scoring rate, and first analyze the root causes of students' mistakes and the psychological process of doing the questions. For example, some teachers have foreseen the students' mistakes, and they have repeatedly emphasized them, but the students are still wrong. There are two possibilities: one is carelessness, which is often caused by poor basic knowledge. This kind of problem is generally understood after students get the test paper and think for themselves, and the teacher doesn't need to explain it again; The second is "misunderstanding". Some flexible questions seem to be understood by the teacher, but I'm afraid I won't do the same questions or make mistakes in the future. In order to overcome the situation of "making mistakes as soon as you listen", let students really understand and master, and let students have more since the enlightenment and discussion, we should not only talk about reasoning, but also tell students how they came up with this reasoning. After discussing and dealing with related problems in mathematics evaluation class, teachers should carefully select one or several groups of intensive variant exercises from multiple angles and in all directions according to the related knowledge, skills, techniques, methods and ideas involved in the problems, so as to deepen students' understanding and mastery of the problems from all angles and give them opportunities for further practice, summary and reflection. The choice of variant exercises is also very important, and the type and difficulty should be grasped well. If you choose well, students' learning effect and consolidation will get twice the result with half the effort. If the choice is not good, students will become more and more confused and at a loss. Don't explain the topics one by one in isolation. We should grasp the essential characteristics of the problem through the superficial phenomena in the topic and explain it in an open and divergent way. Generally speaking, divergent guidance can be carried out from three aspects: "multiple solutions to one question", "multiple links to one question" and "changeable questions" So the preparation work should be very sufficient.
For example, the following is an example of a lecture on accurate figures and significant figures in scientific notation.
(1) Original analysis: Approximation 2. 18× 104 is accurate to hundreds, with 3 significant digits.
Wrong way: 5 percentage points
Student analysis: Students only focus on 2. 18, not counting 104, but the effective number is to change the number into 2 1800, so the reason for the mistake is that students do not accurately understand the number and the form of the number.
Analyze the causes of mistakes, delve into the psychology of mistakes, and make profound reminders and reflections from the perspective of the wrongdoer. )
Student induction: The exact number of digits depends on the original number, and the effective number only needs to look at A in a× 10n.
(2) Consolidation and improvement: the approximate number is 2 1800, with three significant figures.
The approximate value of 3.0× 102 is accurate to ten places with two significant figures.
The approximate value of 300 is accurate to three figures, with three significant figures.
Deepen the understanding of knowledge points in practice, especially the variations of 2. 18× 104 and 2. 18000, and the similarities and differences between 300 and 3.0× 102.
Variant training of mathematics is particularly important in reviewing and commenting.
Second, the form of class
Highlighting students' dominant position is the guarantee of classroom success. In fact, class evaluation is a review of past knowledge. Compared with the teaching of the new curriculum, students' dominant position in class evaluation should be more prominent. Don't let the teacher speak at once. The role of teachers is to organize, guide and instruct students to think actively, explore actively, make bold assumptions and guesses, ask questions, cultivate students' innovative consciousness, and dare to think and speak. Dare to be bold and unconventional, so that students can truly become the masters of lectures and evaluations.
Mathematics lectures and evaluations can't cover everything. There are three ways to solve the problem: self-solving, classmates' help and teachers' guidance. Most students with high scores can solve problems by themselves, and even some problems have been found and solved just after the exam, so such problems do not need time. For the second question, students can discuss and help each other. When students solve problems, students who help students solve problems also get a chance to exercise. Therefore, some time can be reserved in class for students to solve problems through discussion and consultation. It's just that teachers need to explain and comment on some difficult topics, but they should also try to be guides rather than inducers, and students' subjectivity cannot be changed. In addition, although some questions are correctly answered, students especially want to know if there are other simpler, more ingenious, more beautiful and better solutions (especially objective questions). At this time, students can show their magical powers and provide various problem-solving methods. In short, let students "understand the general method, but not necessarily use the general method" and "understand the model, but don't model". It means to know the usual method of solving problems, but you don't have to use this method. Breaking the routine is a weather vane of quality education.
In short, mistakes make students "change"; Ideas and solutions make students "speak"; Pay attention to students' practice. The main thread of students' self-discovery, self-discussion and analysis, self-correction, self-investigation, self-induction and self-solving should run through the whole process of lectures and evaluation.