新课程背景下初中化学课堂教学倡导创建开放的学习环境，促进学生多元化发展，但随着课程改革的继续推进，在实践中课堂教学的开放性、实效性暴露出许多问题。我们必须对课改实践中涌现的问题进行反思，有针对性地思考解决措施，本研究正是基于这样的背景提出来的。本研究将课堂教学的“开放”界定为让学生接触更丰富的课程资源，用更多样化的教学技术手段呈现教学内容，有更多的学生活动和更大的学生思维空间。“实效”是指课堂教学的实际功效，即学生所获得的真实发展。首先，本研究试图结合相关理论探讨开放性与实效性的关系，运用系统科学思想、建构主义理论论证了开放能促进实效，追求实效需要开放。接下来，本研究深入教学实践，分析大量优秀的初中化学课堂教学案例，从实际教学中提炼具体的开放性措施和实效性措施，并通过案例片段揭示措施的实际操作和实施状况。开放性措施研究选择了教学内容的开放、教学技术手段的开放和教学方法的开放这三个维度，在每一维度结合案例提炼了具体的开放性措施。实效性措施研究是在开放性教学的前提下，针对开放性课堂容易出现的实效性问题展开的，重点研究了提高开放性元素本身质量的具体措施和加强教师对开放性元素的引导作用的具体措施。最后，在前面研究的基础上，本研究选择了一个具体内容“质量守恒定律”，针对教师基于相同内容的不同教学处理进行研究。根据15位教师不同教学处理的横向比较和一位教师的两节课不同教学处理的纵向比较，探讨了如何综合运用开放性措施与实效性措施来实现课堂教学的实效性。

Chemistry class teaching in junior high school advocate that it should set up open learning environment on the background of the new curriculum, which is able to promote students diversiform development. When we implement curriculum innovation, there are many problems discoved about the opening and effectivity of class teaching in practice. We should reflect on the problems discoved amonge curriculum innovation in practice, search for the measure to solve the problems pertinencily. So this research is proposed.The definition of “opening” and “effectivity”of class teaching has been proposed in this paper firstly. “Opening” means more abundant curriculum resource for students, more diverstiform instrument to show didactical content, more activity and bigger mental space for students. And, “effectivity” means the actual effort of class teaching, that is the actual development of students.First, we study on the relation of opening and effectivity theoretically by system ology and constructism in this reseach. Which demonstrate that opening is able to accelerate effectivity, and pursing effectivity need open environment.Then, this reaseach go deep into the practice of class teaching. We analyse many outstanding case of chemistry class teaching in junior high school. We epurate idiographic measure of opening and effectivity from it. We also show how it is and what it is in practice by the segment of case in this paper.At last, based on the measure of opening and effectivity, we choose a special content “ mass conservation law”，then investigate teachers’ different disposal on the content of “mass conservation law”. According to the difference amonge diversiform disposal of 15 teachers on the same content and two kinds of disposal of one teacher on the same content, we investigate how to apply the measure of opening and effectivity in chemistry class teaching synthetically to achieve effectivity.