首先联系除法、分数旧知识,让学生解答课本P.18的两个实例,引入比的意义。可先通过例1提问写出两个除法算式:①求长是宽的几倍用什么方法计算?(除法)这是什么除法?(包含除法)(板书:长是宽的几倍?3÷2=1(1/2))②求宽是长的几分之几又用什么方法计算?(除法)谁作被除数?谁做除数?(宽做被除数,长做除数)为什么?(这是求甲数是乙数的几分之几的分数基本应 First of all, contact the division, score the old knowledge, let students answer two instances of the textbook P.18, the introduction of ratio of significance. Can be asked first through the example 1 Write two division formula: ① seeking length is several times the width of what method to calculate? (Division) What is this division? (Including division) (Board: long is several times the width? 3 ÷ 2 = 1 (1/2)) ② What width is a fraction of the length and what method to calculate? (Division) Who is the number of divisors? Who do the divisor? (Wide dividend, long divisor) Why? A number of scores is a fraction of the number of B should be basic