Goals:
1. Students will learn the five processes in the water cycle which water moves through.
2. Students will understand that water moves through the water cycle continuously.
Resources:
1. http://www.windows.usmich.edu/earth/water/water_cycle.
Water Cycle, the water cycle never ends because the salty ocean water constantly supply fresh water to the continents.
2. Textbook: if applicable.
3. The water cycle. Home curriculum weather. Internet address, http://168.99.195.252/curric/weather/adptety/watercycle.html
4. How water moves through the cycle. Internet address, http://www.fwee.org/hlogic.html
5. Materials
a. Evaporation activity materials: small dishes, table spoon, water, sun lamp or other light source, plastic wrap or cover.
b. Condensation activity materials: A clear 2 liter plastic bottle one for every 4 students. One box of wood matches, a temperature strip for every bottle, an eye dropper or other containers of water.
c. Precipitation activity materials: A hot plate or other heat source to boil water. A Pyrex or other container with a handle, ice cubes, a pot for boiling water, and a pie pan.
Time:
Lesson will take between 3 to 4 hours.
Procedure:
Background Information-
The Earth's water is used over and over again. The water cycle is the continuous movement of water from ocean, to air, to land, and then back again. During the water cycle, the sun heats the earth's surface causing the water to evaporate into a vapor. This vapor rises into the air (earth's atmosphere) where it cools and condenses into liquid droplets. Once these droplets of water grow larger, they become heavy and fall to the ground as rain or snow. Another term for rain or snow is precipitation.
Water is held or stored in glaciers, lakes, and underground reservoirs. Water can move from these places by streams and rivers, then return to the oceans, then be used by plants and animals, or evaporated back into the earth's atmosphere.
Step 1- Introduction questions: Where do you think your drinking water comes from? Is it the same water that people hundreds of years ago drank?
Step 2- Students will break up into teams of 4 or 5 students.
Each team of students will complete each activity.
Step 3- The evaporation activity: Have each team get two dishes. Put one small tablespoon of water in each dish. Place one dish in the sunlight or in the light source. Let the students decide if they want to cover their dishes or leave them uncovered. Place the second dish in an area out of the sunlight or light source. The students will then observe and record what happens.
Step 4- Teams will answer discussion questions on their own sheets of paper. Write questions on the chalk board.
A. Which dish evaporated faster?
B. Where did the water go?
C. How did the water evaporate?
Step 5- Each team will discuss questions before condensation activity.
A. What makes air warmer?
B. What happens to warm air?
C. What makes clouds?
D. How are clouds made?
E. What three things are necessary to form clouds?
Step 6- The condensation activity: Record temperature changes in a closed bottle. Tape temperature strip in the bottle so it can be read. Then screw the cap on the bottle tightly. Lay the bottle on its side so you can easily read the temperature strip. Read and record the temperature of the air inside the bottle. Use both hands to squeeze the bottle as hard as you can. After about one minute, read the temperature strip again. Stop squeezing the bottle and read the temperature strip again after one minute.
Step 7- Students will answer discussion questions:
a. What happened to the air inside the bottle when you squeezed the bottle?
b. What happened to the air temperature inside the bottle when you stopped squeezing the bottle for one minute?
Step 8- Students will open the bottle and pour in a few drops of water. Screw the cap on tightly. Swirl the water around the inside of the bottle so most of the inside is wet. Squeeze the bottle and observe the temperature again. Record what happened.
Step 9- Students will lay the bottle on its side, open the bottle and push down to flatten the bottle to about 1/2 its normal size. Have someone light a match, blow it out, and put the match into the bottle while it is still smoldering. Quickly release the sides of the bottle and put the cap on tightly. Now squeeze the bottle very tightly as before for about one minute. Quickly let the bottle pop open. What happens?
Students should have seen a cloud. In this experiment water molecules condense into a cloud inside the bottle. By squeezing the bottle, the air pressure in the bottle increased which raised the temperature. The warmer air caused the water in the bottle to evaporate. The water turned into a vapor and you could see it. Once the bottle was allowed to pop out, the air pressure, as well as the temperature were lowered. This caused the water molecules to condense into a cloud.
Step 10- Teams will discuss the following precipitation activity questions before activity:
a. What is rain?
b. How does rain happen?
c. What is snow?
d. How does snow happen?
Step 11- Before completing the precipitation activity, pose the following questions: What will happen to the bowl of ice? The steam? To the bottom of the bowl of ice? The students will need to focus on these questions during the experiment.
Step 12- Teams will complete precipitation activity: Place a pot of water on a heat source until it comes to a boil. Fill the Pyrex pot with ice. Once the water is boiling, hold the pot of ice over the steam. Place the pie tin or pan underneath, so that the water drips off the Pyrex pot into the pie pan.
Step 11- On a sheet of paper the student teams will answer these questions the following questions:
a. How did the water get on the Pyrex pot?
b. What do you see happening in the pie tin?
c. Which drops were bigger those on the side or on the bottom of the Pyrex pot?
d. How were the big drops formed?
Assessment:
1. On a separate piece of paper, the students will write their explanation of the relationship between air temperature, air pressure, condensation and the formation of clouds in the water cycle. Explanation will be assessed in accordance with "Writing Rubric."
2. Student teams will complete activity questions correctly. Questions will also be assessed in accordance with "Writing Rubric."
3 Student's ability to work with a team will be assessed in accordance with "Team Participation Rubric".
Curricular Strands and Major Concepts:
1. Language arts- describing what happens during their activities. Cooperation and team work.
2. Science- activities involving evaporation, condensation, and
precipitation.
Possible Extension:
1. Investigate the weather pattern of local area.
2. Create a unit dealing with the earth's weather.
Bibliography:
Water cycle. A Never Ending Story. Teachers Resources,
http://www k12.atmos.washington.edu/k12/pilot/water_cycle/whole_cycle/trackerpage.html