随着教学的推进,教材知识不断加深,学生学习的难度相应加大。初中化学学习中,有几道“坎”学生普遍感到比较难以跨越:一是化合价及化学式,学生感到化合价难以理解,化学式书写无从下手;二是化学方程式的书写和有关计算,学生常会感到化学方程式的书写枯燥乏味,根据方程式的计算尤使学生头疼;三是溶液概念不清;四是酸碱盐之间的复分解反应。针对学生普遍 With the advancement of teaching, the knowledge of teaching materials is deepening and the difficulty of student learning is correspondingly increased. Junior high school chemistry learning, there are a few “Kan ” students generally feel more difficult to cross: First, valence and chemical formula, students feel valence is difficult to understand, chemical writing can not start; Second, the chemical equation writing and related calculations, students often feel The writing of chemical equations is boring, according to the calculation of the formula especially for students with headaches; third, the concept of solution is unclear; fourth, the metathesis reaction between acid-base salts. Common to students