Curated OER
Testing Water for Hardness
Students discuss the nature, cause and effect of hard water. Each student conducts a soap test on a sample of hard water where the hardness is known measuring the height of the bubbles produced.
eSchool Today
E School Today: Your Revision Notes on the Water Cycle
Learn about the different stages of the Earth's water cycle, and about processes involving water, including runoff, infiltration, and the differences between hard and soft water.
Other
Culligan: Fundamentals of Water Softening
A brief article about the fundamentals of water softening by ion exchange. Culligan water company walks you through the water softening process. Defines hard water and describes how it is eliminated through specific chemical processes.
US Geological Survey
Usgs: Common Water Measurements
This site from the U.S. Geological Survey provides great definitions of seven measurements that can be taken on water. Includes pH, dissolved oxygen, and turbidity. Click Home to access the site in Spanish.
Science is Fun
Science Is Fun: Soft Water and Suds
For this experiment, students create hard water from distilled water, then test how soft and hard water behave when detergent is added, i.e., how well suds can develop. An explanation of how dissolved minerals affect water's sudsing...