“毫米”是二年级下册“分米和毫米”的内容之一,属于“图形与几何”领域,旨在发展学生的空间观念。在现实生活中虽然有些物体相当短、相当薄,不足1厘米,需要使用毫米这一长度单位,而事实上在二年级学生的生活经验中却是接触得比较少的,就是我们成人对毫米的使用频率也很低。因此对于以形象思维为主的二年级学生来讲,正确建立1毫米实际长度的表象是比较困难的。学生往往能够借助尺,在尺子上找到1毫米,而脱离了尺子,让他们来感知1毫米的实际长度,难度就相对较大,在根据物体的长度特点或 “Mm ” is one of the content of the second grade under the book “decimeter and millimeter ”, belonging to “graphics and geometry ” area, aimed at the development of student space concept. Although in real life some objects are relatively short and relatively thin, less than 1 cm in length, units of millimeters need to be used. In fact, second-graders experience less contact with life experience, that is, we are adults to mm The frequency of use is also low. Therefore, for the second graders based on image thinking, it is more difficult to correctly establish the appearance of the actual length of 1 mm. Students often can use the ruler to find 1mm on the ruler and get rid of the ruler so that they can perceive the actual length of 1mm. The difficulty is relatively great. Depending on the length of the object or