教科版小学科学五年级下册“沉和浮”单元第五课“浮力”中有“测量泡沫塑料块受到的浮力”实验。使用普通弹簧测力计测量浮力,需借助安装在水槽底部的滑轮和细线控制泡沫块浸入水中的深度,同时测出泡沫块排开的水量和受到的拉力,再根据重力、拉力与浮力之间的关系,计算出泡沫块受到的浮力。教材方案如图1所示。一、实验存在的问题该实验方法需建立在“平衡力”的概念认知基础上,因此五年级学生并不能完全理解测量的原理。教 Textbook primary school grade five science under the book “Shen and floating ” unit Lesson “buoyancy ” in “buoyancy foam buoyancy measurement ” experiment. To measure the buoyancy with an ordinary spring dynamometer, the depth of immersion of the foam block in the water should be controlled by means of pulleys and thin lines installed at the bottom of the tank, and the amount of water discharged by the foam block and the tensile force received by the foam block are measured. Based on the gravitational, tensile and buoyancy forces The relationship between the calculated buoyancy foam block. Teaching materials program shown in Figure 1. First, the experimental problems The experimental method should be based on the concept of “balance” based on cognitive, so the fifth grade students do not fully understand the measurement principle. teach