This WATER PURIFICATION WATER CYCLE LAB allows students to investigate how evaporation and condensation can be used to obtain clean freshwater from saltwater. Students learn about the global scarcity of freshwater and then construct a simple solar still that models the natural water cycle.
This activity connects the water cycle to the global challenge of providing clean drinking water and introduces students to the engineering behind desalination and water purification.
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In this activity, students will:
- READ an article about how clean freshwater is limited on Earth, how saltwater causes dehydration, and how engineers solve water supply problems using technologies like desalination and solar stills. After the article, they answer text-dependent questions on a corresponding worksheet.
- BUILD a working solar still using a simple setup that models evaporation and condensation. Uses simple supplies that you probably already have on hand!
- OBSERVE water vapor forming, condensing on a surface, and collecting as freshwater.
- RECORD DATA and observations as the solar still operates.
- ANSWER ANALYSIS QUESTIONS that connect the investigation to real-world engineering solutions for water scarcity.
- USE CLAIM–EVIDENCE–REASONING (CER) to evaluate whether solar stills could realistically provide drinking water for communities lacking freshwater.
EASY Supplies List: large clear plastic container, plastic wrap, large rubber band, small plastic or foam cup, 2 pennies, heat lamp OR access to a sunny window, colored saltwater (salt, water, food dye), graduated cylinder
This activity reinforces the following concepts:
- Evaporation and condensation in the water cycle
- How solar energy drives evaporation
- Salt does not evaporate with water
- How desalination technologies produce freshwater
- Real-world challenges of global freshwater supply
- Engineering solutions to water scarcity
The resource includes:
- Reading passage “Freshwater on Earth: A Limited Resource” (2 pages) with a corresponding worksheet with text-dependent questions (2 pages)
- Solar still lab procedure write-up for students with data and observation table (2 pages)
- Lab analysis questions with CER (2 pages)
- Extensive teacher notes, tips, and “going further” ideas
- Answer key for all sections
Teacher Notes
- Check out my complete WATER CYCLE UNIT!
- The reading “Freshwater on Earth: A Limited Resource” and its corresponding worksheet include both print and digital Google Slides options to assign. The lab portion of this resource is print only – no digital version.
- This investigation is versatile because it can be run in class under a heat lamp OR placed on a sunny windowsill.
- Related standard: MS-ESS2-4 – Develop a model to describe the cycling of water through Earth’s systems driven by energy from the Sun and the force of gravity.
- Answer keys are always included.
- Please note that no part of this water cycle lab is editable.
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