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## #3033. The Water Cycle

Science, level: Middle
Posted Wed Jan 21 08:55:13 PST 2004 by K.A. Pohopin (katieapohopin@yahoo.com).
University of Pittsburgh, Johnstown, Johnstown, PA
Materials Required: lecture notes, pen/pencil, gradebook, markerboard, markerboard markers, markerboard eraser, red pen
Activity Time: 50 minutes
Concepts Taught: the water cycle

Instructional Objectives (Student-centered, observable, and precise statements of what students will be able to do):

By the end of this lesson, the students will be able to...

orally recite the main components of the water cycle using information learned throughout the lesson.
define the terms associated with the water cycle--including evaporation, transpiration, condensation, precipitation, and collection/storage--using information learned throughout the lesson.
list the possible sites where water is stored or collected after precipitation during the water cycle on the "if time permits" worksheet.
sketch a diagram of the water cycle and the stages water takes through it, after researching the topic on the internet and completing the question and answer session.

Introduction (attention getter, anticipatory set, discrepant event, open-ended problem scenario, engagement):

"Take a look at this glass of water. I just got it from the faucet in the ladies bathroom right outside here.
How old do you think this water is?"
take volunteers
if needed, call on people to get some response
Answer: "The water may have fallen from the sky just last week, but the water itself has been around about as long as the earth has, pretty much.
Does anyone know how old the earth is?"
Answer: "It is believed that the earth is 4.55 billion years old
That means that the water in this glass could quite possibly be 4.55 billion years old also."

Estimated time to complete introduction: 5 minutes...this includes "thinking time" and getting responses. This activity may take more time if students are responding well with a variety of ideas.

Developmental Activities (Instructional components that provide opportunities for students to make progress toward intended instructional objectives):
Question and Answer session-->estimated time--15 minutes--**Ask the following questions taking voluntary answers or calling on people as needed. Make sure to give enough time for the students to respond--proper thinking time.
-->Does anyone know how it's possible for this water to have remained here 4.55 billion years?
**By way of the water cycle.
-->Who knows what the water cycle is or how it works?
**The water cycle is the process by which water is always cycling around, through, and above the earth with water continually changing from liquid water to water vapor and ice.
-->Does anyone know the main events or processes that occur during the water cycle?
**evaporation, condensation, precipitation, and collection/storage
**to convert or change into a vapor
-->How exactly is water changed into a vapor?
**the water is heated by the sun
-->Where on Earth is the water that is evaporated? Where does it start or come from?
**rivers, lakes, and oceans
-->Where does the water vapor go?
**into the air
-->What about the water in and on plants? What happens with that water?
**it is removed as water vapor through transpiration
**Transpiration is the process by which plants lose water out of their leaves and the water rises into the air as water vapor.
-->What happens to the water vapor next?
**CONDENSATION
-->What exactly is condensation?
**it's when the water vapor in the air gets cold and changes back to a liquid form.
**The vapor condenses on tiny particles of dust, smoke, and salt crystals to form clouds.
-->Where besides the water cycle can you see condensation take place?
**on the outside of a glass of ice water on a hot summer day
-->Where did the water on the outside of the glass come from?
**The water did not soak through the glass, rather, it came from the air. When water vapor in the warm summer air touches the cold glass, it turns back to a liquid.
-->What is the next step in the water cycle, after condensation?
**PRECIPITATION
-->Can someone tell me what precipitation is?
**It occurs when so much water has condensed that the air cannot hold it anymore.
**The clouds get heavy and the water particles fall back to the earth in the form of rain, hail, sleet, or snow.
-->When the precipitation falls to the earth, which stage of the water cycle occurs?
**COLLECTION/STORAGE
-->Where is water stored on Earth?
**lakes, rivers, streams, oceans
-->Where else might water go when it falls back to Earth?
**the water may end up on land where it will soak up into the earth or run over the soil and collect in the oceans, lakes, and rivers.
-->Does anyone know what happens to the water that soaks into the earth?
**that water becomes ground water that plants and animals use to drink.
-->Does anyone know what happens next to water particles that are on Earth?
**the water is heated by the sun while on Earth and evaporation occurs.
**the water cycle begins over again...and again...and again.
-->When does the water cycle stop?
**never!

Computer Lab Session-->have computer lab already reserved prior to class.

**Inform the students that the class is now going to go to the computer lab to research the water cycle. The goal of the students is to find a diagram of the main components of the water cycle online. This can be done through searching search engines of any sort. Remind them that the diagrams will be printed out and handed in. They will be used for a later activity for another day.
**Allow the students to chose a partner to work with in the computer lab--only two students permitted at one computer.
**While in the computer lab, teacher must observe actions and make sure students stay on track and are not researching inappropriate information.
**Collect the diagrams from each group before leaving the lab--there may be duplicates of the same diagram.

(estimated time to complete--15 minutes)

If Time Permits Activity

Have the students complete the "If Time Permits" worksheet without any notes, textbook, or help from classmates.
If time does not allow for this activity, assign the worksheet for homework and collect it in the following class period.

Assessment/Evaluation (How you and the students will know that they learned. May be formative or summative):

Have a brief "backward" question and answer session.
Review all the material learned today or any trouble spots that the teacher may recognize along the way.
A backwards Q & A session allows the teacher to be asked any questions from the students--for the students to test the teacher's knowledge of the subject matter and to get the students thinking about what types of questions they might have on the topic.
In last month's wrap-up session for the chapter, students seemed to enjoy this and learn from it also.
(estimated time to complete--5 minutes)

Conclusion (Closure; a planned wrap-up for the lesson):

Have the students think about what the water in this glass has been "around to experience."
This ties in history with the sciences and the water cycle.
The water could have been present when the dinosaurs roamed the earth, for Christopher Columbus to sail across to discover the new world, for many things.
Remind the students, that the water has been present since the world began--4.55 billion years ago.
Encourage them to be creative.
Take volunteered answers or call on those who are not participating to keep them involved.
(estimated time to complete--5 minutes)