一、设计思想 本课是对教科版教材《马铃薯在水中是沉还是浮》一课的改造(由于三年级已全部上过本课,只能在四年级试教,所以本教案针对四年级的学生做了适当的调整)。在知识目标上,由原来的是否研究“为什么会浮”这个问题的模棱两可,转变为明确地研究“怎样使之浮”这一类问题,即在水中加足盐或糖并使其溶解,能使马铃 First, the design ideas This lesson is a textbook textbook “potatoes in the water is sinking or floating,” a class of transformation (as the third grade has been on the class, only in the fourth grade teaching, so the lesson plans for the fourth grade Students made the appropriate adjustments). From the ambiguous question of whether or not “floating” should be studied on the objective of knowledge, the question of “how to make it floating” should be changed to a clear study of adding salt and sugar to water and dissolving it Make the bell