论文部分内容阅读
在小学现行教材里,没涉及“弧长”概念,所以教学中出现求半圆弧长时,为避开这一名词,不少教师改用“半圆周长”来叙述.殊不知这样一改,就把两个不同的概念弄混了,出现了知识性错误.事实上,“半圆周长”是指半圆弧长与圆的直径长度之和,而“半圆弧长”即圆周长的一半.两者的区别在于前者含圆的直径,而后者不包括圆的直径.在教学中遇到这一问题时,教师不应该讲“半圆弧长”的术语,更不能用“半圆周长”来替代,怎么
In the current primary school textbooks, there is no concept of “arc length”, so when seeking to find a semicircular arc in teaching, to avoid this term, many teachers use “semi-circle circumference” to describe. In such a change, two different concepts were confused and a knowledge-based error occurred. In fact, “semicircular circumference” refers to the sum of the semicircular arc length and the diameter of the circle, and the “semicircle Arc length ”is the half of the circumference, the difference between the two is that the former contains the diameter of the circle, while the latter does not include the diameter of the circle.In the teaching of this problem, teachers should not say “The terminology, but can not be replaced by ” semicircular circumference ", how