Summary
This module integrates the hydrology, solar energy, measurements and cooperative learning
processes.
Connection to the Curriculum
This module demonstrates to students a method of purifying condensation and
evaporation. It allows the students to witness a hydrologic cycle of the earth. Math
activities include the predictions and actual measurements of water and salt being
introduced and produced from the still which could result in formulas for future water
needs.
Time calculations would be necessary. Business issues could be included for those would wanted to begin a business of solar stills. Environmental issues of pollution and chlorinated water would be easy to establish. Writing act ivies could include what processes took place. How third world countries would benefit from these low cost stills? Why don't more people use solar stills to distill their water instead of purchasing it at the store?
Time
This module will take approximately one week with one to two hours of instruction
per week to complete. Once the still is built its operation could continue all year.
Season
This module can be used anytime throughout the school year.
Materials
paper cup
pencil
one clear plastic bag
water
salt
TEKS:
5.1A,B 5.2A thru E 5.4A,B
5.6B 5.8A
Objectives
(1) Students are introduced to the need for fresh water in human survival.
Students will keep a running record of all water consumed for one week through observation
recording their results daily in a journal.
(2) Students will be introduced to various methods of pollution through direct observation. Visiting the local water plants will assist us in what wastes are polluting our water ways.
(3) Students will build a solar still recording water and salt introduced into the still. Records will also be kept on how much distilled water is produced from the still.
Procedures
1. Students will research the hydrologic cycle finding that water changes form
but is never destroyed as it travels through the cycle.
2. Students can further understand how the hydrologic cycle process operates by making their own clouds experiment. See making clouds.
3. Students will build a solar still which operates on the basic principle of evaporation and condensation.
4. Students will place the solar still in a spot that gets full sun. Have the students add salt water to the cup, measuring the amount of water and salt solution. Have students check the bag every day recording the distilled water. Students may add more salt water solution as needed to maintain a constant flow on the still.
clear plastic bag cup with salt water solution
Questions
What happens to the water in the cup?
What is the source of the condensation in the bag?
What does the water that collects in the bottom of the bag taste like?
How can the still be more effective?
If you were on a deserted island without a fresh supply of water what could you use?
Expanding the Lesson
Students may improve upon their stills by using a black plastic bag, aluminum
foil, and other materials as needed.
Students will find ways to produce more water in a shorter period of time.
Expand the lesson to include pollution, sickness, and disease from the lack of a safe water supply and waste water treatment.
Students can also estimate the costs of producing solar stills for household and commercial uses on the retail market.
Internet Resources
El Paso Solar Energy Association.
http://www.txses.org
State of Texas State Energy Conservation Office. http://www.txses.org/epsea/stills.html
Solar Stills
http://www.accessone.com/agua del sol
http://www.zekes.com/aguadelsol/index.html
© Wayne Cooper 1997
© BellNET 1997
BellNET WebMaster
Last updated on August 23, 2000.