在第十册“正比例”教学中,不少教师把例4、例5放在同一堂课里教,例4详讲,例5一笔带过。我从质量检查中发现,这种教法,学生对例5一类题目理解不深,效果不佳,其中,对单位不必统一就进行计算,尤为困惑。例5的题后“注意”说:“例5中的‘吨’不必化成公斤,只要两种量中相对应的数用相同的单位就可以了。”这里的“不必” In the tenth volume “proportional” teaching, many teachers put Example 4, Example 5 in the same class teaching, Example 4 in detail, Example 5 a passing. I found from the quality inspection, this method of teaching, students on the first five cases of a type of understanding is not deep, ineffective, of which units do not have to be calculated on the unity, especially perplexed. The “caution” in Example 5 says: “The 't' in Example 5 does not have to be converted into kilograms, as long as the corresponding numbers in both quantities are given in the same unit.” Here, “do not have”