PREINSTRUCTIONAL

• Students will be able to define evaporation.
• Students will see a demonstration of actual evaporation, and the time difference in evaporation between sunny and shady environments.
• Students will discuss how heat effects evaporation, particularly as this applies to a desert environment.

• Water
• One Sponge
• Ruler
• One Shallow pan for every pair of students

DURING INSTRUCTION

1. Wipe a damp sponge across the chalkboard, and wait until dry spots begin to appear.
2. Ask the children where the water went.
3. If the word "evaporated" was not mentioned, explain that the water evaporated, changed from a liquid to a gas called water vapor. Write this word on the board.
4. Ask the group to think of other examples of things that water evaporates from (clothesline in the sun...) Ask the class to think about how heat affects evaporation.
5. Explain to students that they will be placing two pans of water outside - one in the sun, the other in the shade. Ask them to record their predictions of what will happen in their science journal.
6. In pairs, have the students place a shallow pan that contains two inches (5cm) of water in a sunny (or warm) spot, and another pan with the same amount of water in the shade (or a cooler spot). Ask the students to record where they placed the pans in their journals. Also ask them to record the amount of water in each pan. Leave for the rest of the day.
7. At the end of the day, measure the water in the two pans. (There will be less water in the pan that was placed in the warmer area because heat speeds up evaporation)
8. Return to the classroom, and discuss how this information affects the desert environment.
9. Ask the students to record reactions in their journals.
10. Record results and reactions in journals.

• Did the students demonstrate a working definition of evaporation in the class discussion?
• Did the students connect the quicker evaporation rate with the present heat conditions?
• Did the students contribute to the discussion of how the heat affects the desert environment? Were their contributions on the right track?
• Were the student journals reflective of the phenomena taking place? Did they show understanding by attributing the quicker rate to the warmer conditions?

• If there is no sunny spot available, the heater in the classroom may be used.
• If a student does not understand, perform an experiment using two damp pieces of material. On one, use a blow dryer to dry. Leave the other one to dry. When the first one dries faster, ask the student what it is about a hair dryer that dries things (heat).