科学考察课是小学自然常见的课型之一,这类课一般都要求学生进行现场考察,然后取样研究,最后做出考察结论。但有些内容比如《火山和地震带给人们的信息》、《卵石是怎么形成的》等,因受条件的限制,要进行现场考察是有困难的。对此,可利用电教手段来弥补这方面的不足,也能收到较好的教学效果。现以《卵石是怎么形成的》(第五册第十九课)为例,谈谈具体的教法。一、投影画面,分段考察考察卵石的存在和来源时,教师在课前绘制了由四个画面构成的组合幻灯片,画面由近及远分别表示下游、中游、上游河道和高山。先在屏幕上投影下游河道,指导学生考察下游河道的特征。在画面的启发下,学生有身临其境的感觉,亲眼见到下 Scientific expeditions are one of the most common types of lessons in primary school. Such courses generally require students to conduct site visits and then take samples to study and conclude the survey. However, there are some contents such as “Information from Volcanoes and Earthquakes” and “How Pebbles are formed”. Due to the restriction of conditions, it is difficult to conduct site visits. In this regard, the use of audio-visual methods to make up for this deficiency, but also receive better teaching results. Now take “Pebble is how to form” (Volume V, lesson nineteenth), for example, to talk about the specific teachings. First, the projection screen, sub-inspection study Existence and source of pebbles, the teacher before the lesson drawn by a combination of four screen slide, the picture from the near and far, respectively, said the lower reaches, middle reaches, the upper reaches of the river and the mountains. Project the lower reaches of the river first on the screen to instruct students to examine the features of the downstream river. Inspired by the pictures, students have the feeling of immersion and see it with their own eyes