Connecting prior knowledge and reflecting overall teaching - Taking the teaching of "Image of Sine and Cosine Function" as an example
串联前知，体现整体教学——以“正余弦函数的图像”教学为例

摘要

“正余弦函数”是高中初等函数学习的重要一环，在学习了指数、幂、对数三种初等函数之后，学生初步构建出初等函数的学习逻辑，正余弦函数的图像这节课的学习可以沿用初等函数学习逻辑，搭建起初等函数学习的整体路径，又通过与本单元弧度制、三角函数定义的关联，引出本节课核心画图方法——几何画图法，完成对正余弦函数的探究，学生在与前知联系的过程中体会知识学习的整体性、关联性。

Abstract

"Sine and Cosine Function" is an important part of the learning of elementary functions in high school. After learning the three elementary functions of exponent, power and logarithm, students initially construct the learning logic of elementary functions. The learning of the image of sine and cosine function can follow the learning logic of elementary functions and build the overall path of learning elementary functions. Through the association with the definition of radian system and trigonometric function in this unit, the core drawing method of this lesson - geometric drawing method is introduced to complete the exploration of sine and cosine functions. Students experience the integrity and relevance of knowledge learning in the process of connecting with prior knowledge.