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After reading "Vanishing Forest" (p. 18), try this activity.

PREDICT

In which container would you expect water to evaporate e·vap·o·rate
v.
1. To convert or change into a vapor; volatilize.

2. To produce vapor.

3. To draw or pass off in the form of vapor.

4.
, or change from a liquid to a gas, more quickly: one with a larger or smaller surface area (area that is exposed)?

MATERIALS

1 measuring cup * 1 disposable disposable Nursing adjective Referring to that which is discarded or disposed of noun An item used in health care-related Pt contact which is discarded after use–eg masks, gloves, gowns, needles, paper products, syringes, wipes. See Biohazardous waste.  loaf pan (10.5 cm by 23 cm, or 4 in. by 9 in.) * 1 mug (0.5 L, or 2 cups) * water (550 ml, or 2.2 cups) * 2 paper towels * 2 plastic plates * graph paper * pencil

PROCEDURE (PART 1)

1 Pour 250 ml (1 cup) of water into a loaf pan. Pour the same amount of water into a mug.

2 Place both containers in a sunny place. Note the time of the day.

3 You will keep track of the amount of water in both containers for five days. Create a data table to help you organize your findings. For Day 1, record "250 ml" as the water amount for the pan, and also for the mug.

4 The next day at the same time, pour the remaining water from the pan into a measuring cup. Record the water amount.

5 Pour the water back into the pan, and place the pan in a sunny spot.

6 Repeat Steps 4 and 5 with the mug.

7 Repeat Steps 4 through 6 every day for three more days.

8 After Day 5, create a double-line graph with the data. (Hint: The "day" will go on the x-axis See x-y matrix. , and the water amount will go on the y-axis.)

CONCLUSIONS (PART 1)

1 Study your graph. From which container did water evaporate faster: the pan or the mug?

2 How did each container's surface area affect the rate of evaporation evaporation, change of a liquid into vapor at any temperature below its boiling point. For example, water, when placed in a shallow open container exposed to air, gradually disappears, evaporating at a rate that depends on the amount of surface exposed, the humidity ?

1. The water in the loaf pan should have evaporated evaporated

reduced in volume by evaporation; concentrated to a denser form.
 more quickly

2. Surface area affected the results The loaf pan has a larger surface area than the mug. With a larger surface area, the loaf pan exposed more of the water's surface to the air, allowing it to evaporate faster. The mug has a smaller surface area So less of the water's surface was exposed to air, hindering hin·der 1  
v. hin·dered, hin·der·ing, hin·ders

v.tr.
1. To be or get in the way of.

2. To obstruct or delay the progress of.

v.intr.
 its evaporation.

PROCEDURE (PART 2)

1 Use what you learned in Part 1 to predict which of the following would retain more water: a flat, broad leaf or a needle-shaped leaf.

2 Place a paper towel flat onto a plastic plate. This represents a tree's "flat, broad leaf."

3 Tightly roll up one paper towel lengthwise length·wise  
adv. & adj.
Of, along, or in reference to the direction of the length; longitudinally.

Adj. 1. lengthwise
, and place it onto another plastic plate. This is a "needle-shaped leaf."

4 Pour 25 ml (0.1 cup) of water evenly over each paper towel.

5 Observe both paper towels: How wet does each paper towel look and feel? Record your observations.

6 Place both plates in a sunny spot.

7 After three hours, observe the paper towels again. Record your observations.

CONCLUSIONS (PART 2)

1 Which paper towel had retained more water after three hours?

2 How could needle-shaped leaves help a coniferous con·i·fer  
n.
Any of various mostly needle-leaved or scale-leaved, chiefly evergreen, cone-bearing gymnospermous trees or shrubs such as pines, spruces, and firs.
 tree retain water?

1. The rolled-up paper towel should have retained more water than the flat paper towel That's because a flat paper towel has a larger surface area than a rolled-up one, allowing the water to evaporate more quickly from the flat towel.

2. Because needle-shaped leaves have a smaller surface area than flat, broad leaves, water would evaporate more slowly from a needle leaf. A slower rate of evaporation would allow a conifer conifer (kŏn`ĭfûr) [Lat.,=cone-bearing], tree or shrub of the order Coniferales, e.g., the pine, monkey-puzzle tree, cypress, and sequoia. Most conifers bear cones and most are evergreens, though a few, such as the larch, are deciduous.  tree to conserve more water than if the tree had flat, broad leaves
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Title Annotation:HANDS-ON SCIENCE; experiment
Publication:Science World
Date:Mar 27, 2006
Words:584
Previous Article:Vanishing forest: a northern forest is disappearing at a rapid pace--that spells trouble for billions of animals.
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