一、教材研究小学教材在分数里安排了分数的基本性质 ,主要是为约分、通分作准备。其实 ,分数的性质包含三个内容 ,一是分母不变 ,分子扩大若干倍 ,分数值也扩大同样的倍数 ;二是分子不变 ,分母扩大若干倍 ,分数值就缩小同样的倍数 ;三是分子、分母同时扩大（缩小）若干倍（零 First, textbooks Primary school textbooks in the scores arranged in the basic nature of the scores, mainly for about points, pass points to prepare. In fact, the nature of the score contains three elements, one is the same denominator, the numerator to expand several times, the fractional value also expand the same multiple; the second is the numerator, the denominator to expand several times, the fractional value to reduce the same multiple; Numerator, denominator while expanding (narrowing) several times (zero