摘 要:随机思想成为人们生存的必需的基本素质之一。在高中概率学习中,学生对概率的频率定义与古典概型的理解存在明显的欠缺。作为高中现行新教材的重要内容,如何搞好概率教学,的确需要我们认真研究。
在高三概率复习前夕,进行一次概率测试,在测试分析的基础上,采取有针对性的教学策略,利用计算机模拟试验复习频率定义;用各种模型进行古典定义的教学;运用实例辨析互斥事件与相互独立事件;借助各种概率模型描述随机变量分布列。按这条主线有针对性的进行复习后,分五次分别对复习效果进行检查,并通过每次检查,总结得失,取长补短,顺利完成高中概率的教学工作。
通过概率教学,笔者得到以下结论。首先,频率定义与古典概型是概率的基础知识,并且为概率的后续学习提供坚实基础,因此它们的教学尤为重要。其中计算机模拟手段在概率的频率定义教学中效果明显,并且直观模型在古典概型教学中的作用也相当明显;其次,通过概念教学与解题教学的结合可以帮助学生深刻理解互斥事件与独立事件;最后,随机变量的分布列作为概率基础知识,期望以及方差的计算都是以分布列为基础的,因而,强化分布列的教学是这部分内容的重中之重。
概率是一门不确定性的数学,它与中学数学中长期占统治地位的确定性数学有很大的不同。为了适合高二、高三学生的年龄特点,教学中应强调概率的基本概念,尽可能地建立有利于揭示问题本质的概率模型,从教学方式、思维方式以及学习方式等三个方面培养学生随机观念,只有这样,才能为学生的继续深造打下良好基础。
关键词:概率教学;概率概念;概率模型;教学策略;随机观念.
Abstract :Random mathematics consciousness is becoming a basic cultivation of people. In the teaching of Probability in senior high school lie obvious inadequacies in students’ comprehension of Probability definition for Frequency and Equiprobability models. How to teach the contents of probability on the textbooks at present in common senior high school exactly needs us to study.
In advance of reviewing probability for Senior Three students, the author gave an exam of probability. On the basis of analyzing the results, the author carried out a group of teaching strategies, the author reviewed the definition of Frequency by computer imitation trials and Equiprobability models by various Probability models, and distinguished Exclusive Events and Independent Events by examples, and described Variable Distribution by means of various Probability models. Reviewing purposely, according to this dominant clue, we checked reviewing effects for five times. To each exam, we summed up disadvantages and persisted in advantages, succeeding in completing the teaching of probability.
Therefore, the author drew some conclusions of probability teaching for Senior high school students. First of all, because the teaching the definition of Frequency and Equiprobability models are basic knowledge of Probability, and they lay a solid foundation for the subsequent studying probability, the method of computer imitation trials in the teaching of Frequency has obvious effect, so does the audio-visual models in the teaching of Equiprobability models. Secondly, the combination in concept and problem teaching can enhance profound comprehension of Exclusive Events and Independent Events. Finally, because Distribution is basic knowledge in teaching probability, meanwhile, the calculation for Expected Value and Variance also are based on Distribution. Thus, Distribution is the most important in teaching them, it needs to give more emphasis.
Probability was an indefinite mathematics and it was different from definite mathematics, which took a dominant position for a long time in middle mathematics. To meet the demands of students’ age in Senior Two and Three, we should emphasize the basic concept of probability and set up probability models as much as possible to explore problems in nature. So the students’ Random-Principle would be developed from the methods of teaching, thinking and studying. Only in this way, we can lay a solid foundation for students’ further studies.
Key Words: Probability teaching; Probability concepts; Probability models; Teaching strategies; Random-principles.
一、问题的提出
随机现象在日常生活中随处可见,概率思想与随机观念成为人们生存的必需的基本素质之一,生活先于课程将统计概率推倒学生的面前。概率内容作为高中数学的基础知识是时代的需要。2003年4月教育部颁布了《普通高中数学课程标准(实验)》,把统计与概率内容作为一个基本模块,同代数、几何以及三角函数同样重要,更加说明高中阶段学习统计与概率的重要性。
由于概率与统计是现行教材的新增内容。近几年概率内容相对稳定(参考人教版高中数学第二册(下 )2003年10月第一版、第三册选修(Ⅱ)2004年6月第一版概率部分),而且全国高考理科数学(必修+选修(Ⅱ))在考查概率与统计内容时,主要以考查概率知识为主。因此,本研究主要针对概率与统计基础知识───高中概率内容的教学。