本册教材的主要有四则运算、运算定律与简便计算、小数的意义与性质、小数的加法和减法、三角形、位置与方向、折线统计图、数学广角和数学综合运用活动等。涵盖了数与计算、空间与图形、统计与概率、数学思想方法方面的。本册教材的重点有运算定律与简便计算、小数的意义与性质、三角形、小数的加法和减法。难点是位 The main textbook of this book has four operations, arithmetic laws and simple calculations, the meaning and nature of decimals, addition and subtraction of decimals, triangles, location and orientation, line charts, mathematical wide-angle and comprehensive use of mathematical activities. Covers the number and calculation, space and graphics, statistics and probability, mathematical thinking and methods. This book focuses on the teaching of law and simple calculations, the meaning and nature of decimals, triangles, decimal addition and subtraction. The difficulty is bit