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Anticipatory Set a. Present the opening scenario on the first activity page. Explain that the “paper on hand” is paper towels. Dip your hand in water and press it for a few seconds against a paper towel, pushing with the other hand to make it as flat as possible. Ask the first Key Question, “How can you make the wet handprint disappear?” Have the students think about this silently while distributing the page, cut in half. Background a. The Water Cycle i. Water can change from liquid to gas to solid, all states of matter, which occur in the water cycle. Through evaporation, the liquid in a lake changes to water vapor and rises into the air. Depending on temperature and other weather conditions, the water vapor will eventually condense and fall again to Earth as liquid (rain) or solid (snow, sleet, or hail). b. Evaporation Variables i. The rate of evaporation varies due to heat, wind, relative humidity, and surface area. Water evaporates more quickly as the heat from the sun intensifies, the wind strengthens, the relative humidity decreases, and the surface area expands. Clothes dryers, hair dryers, light bulbs, and fans simulate nature by applying “heat” and/or “wind” to hurry the drying process. The focus here is on heat and wind, and to a lesser extenct, on surface area. Outdoors, comparisons can be made between sunny and shady spots or windy and wind-shielded locations. Abstract a. After experimenting with making a wet handprint on paper towel disappears, students will use the scientific method to test variables, which may affect the rate of evaporation and relate these variables to weather conditions. Lesson Plan a. Goal i. In this lesson students will learn that the rate of evaporation changes, some of the variables that affect these changes, and the scientific method. b. Content Objectives i. After completing this lesson, students will be able to: 1. Measurement a. Time b. Volume 2. Whole Number Operations 3. Graphing
2 4. Meteorology a. Water Cycle 5. Scientific Method c. Materials i. Paper Towels ii. Water iii. Water Containers iv. Tools for Measuring Water v. Watch or clock with second hand vi. Light Bulb vii. Hair Dryer viii. File Folder ix. Scissors x. Glue d. Estimated Time i. 1 week e. Procedure i. Instruct each student to get a paper towl, make a wet handprint, and try to dry it quickly without special equipment. Blowing and fanning are two options. ii. Have students record the time needed to dry the handprint and describe their methods. Help, as needed in determining elapsed time using a clock face or by subtraction. iii. Guide class sharing of methods and drying times. Ask them for questions or concerns they have. Lead into a discussion of a fair test, the key in making valid comparisons. iv. Continue the discussion, explaining that students will be doing further testing to answer the second key question, “How can the rate of evaporation be changed, if at all?” v. Divide the class into groups and give them the planning page. vi. Have groups discuss possible ways to change the rate of evaporation and decide on the method they want to try. After obtaining your approval – based on safety, available materials, and variation from other group proposals- instruct the students to complete the page. vii. Give time to collect the necessary supplies. Discuss whether timing will be done to the nearest minute or nearest second. viii. Have groups implement their plans and prepare a display of their investigation on large construction paper or a file folders ix. Ask each group to use their display to make an oral presentation to the class. When all the groups have finished, hold a concluding discussion. f. Closure, results, and follow - through activity (extensions) i. Lead a discussion with the following questions 1. Was your test fair? Controlled Variables
3 2. What different ways were used to try to change the rate of evaporation? 3. How do the ways we used to evaporate water relate to nature? Fans – Wind, Light Bulbs – Sun 4. Under what conditions on Earth would a lot of water evaporate? 5. If you were in a desert, how could you keep water from evaporating quickly? ii. Weather connections 1. Unequal heating of Earth, causes changes in evaporation rates 2. Warmer it is – the faster the water molecules move and evaporate 3. This causes an increase in humidity, or the amount of water in the air, and the formation of clouds iii. Extensions 1. Journals: Make a list of local sources of evaporating water, both indoors and outdoors. Pass out final worksheet 2. Competition between teams of who can get the same amount of water evaporated the fastest. 3. What if we changed the kind of paper towel? g. Standards i. National and State Science Content Standards 1. N.S.1 Properties and changes of properties in matter a. C.S.2 Students will explore, demonstrate, communicate, apply, and evaluate the knowledge of physical systems. i. Science Curriculum Frameworks Physical Systems 1. P.S. 2.1 Demonstrate an understanding of the states of matter and describe the various combinations of matter (mixture & compounds) a. What is the relationship between temperature, pressure, and physical state? h. Assessment i. Presentation: Completion 25 % Neatness 25 % Accuracy 25 % Graphs 25 % Inquiry-Based Activity a. The level of inquiry for this exercise is 2. The problem is given and the result is unknown. Specifically the following parts of the exercise are inquiry based.
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4 i. The students are asked to predict how much time it will take for the water to evaporate. ii. Next, the students will measure the rate of evaporation iii. They will then change their prediction based on their measurements. iv. They are then asked many inquiry-based questions. v. To conclude they graph their results and present their findings.