SCIENCE CONCEPT: The sun provides our planet with energy. The sun's heat energy makes the water move, and causes water tp change form and evaporates into the air. STUDENT OBJECTIVE: The student will observe that water left in an open container will disappear or evaporate into the atmosphere, whereas water in a closed container will not evaporate. OVERVIEW: Students will compare and observe how water evaporates from a paper towel that is left open in the air and a paper towel placed in a plastic bag.

PREPARATION TIME: 30 minutes. LESSON TIME: 30 minutes. TEACHER PREP: Label paper towels with student names and use a string to tie a clothesline across the room. WORDS TO KNOW: evaporation evaporate condensation condensing

TEACHER TEXT:

A glass of water looks very calm left alone, but the molecules are very busy moving faster and faster as the water becomes heated. With sufficient heat the molecules break their cohesive bond and escape into the atmosphere. This is evaporation. On the other hand, when the water molecules touch a cool object, they condense as water droplets on the glass. Examples of this can be seen as dew on the grass, water forming on a mirror after someone has taken a bath or shower, or water condensing on the outside of a cool glass.

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Last modified: Fri Apr 3 13:07:10 PST 1998

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