“水的三态变化”教学单元(自然第一册第十至二十课),是在让学生利用各种感官初步认识水之后,为进一步认识水的三态变化规律,并把这一规律运用在自然界中,认识雾、露、霜、雨等现象而安排的。这一单元包括《水的蒸发和沸腾》、《水蒸气的凝结》、《冰》和《水在自然界里的循环》等内容,通过这一单元的教学,应达到以下目的。1 从知识方面讲,应使学生认识水的 “Water tri-state change ” teaching unit (the first volume of natural volumes tenth to twenty), is to allow students to use a variety of sensory preliminary understanding of water, in order to further understand the water tri-state changes, and put this A law used in nature, understanding fog, dew, frost, rain and other phenomena arranged. This unit includes the contents of “evaporation and boiling of water”, “condensation of steam”, “ice” and “circulation of water in nature”. The teaching of this unit should achieve the following objectives. 1 In terms of knowledge, students should be made aware of water