Measure water quality to understand human impact

Time to complete lesson 

Six 50-minute class periods 

 Learning objectives:

• Students build analog and digital electrical conductivity (EC) sensors using instructions.
• Students calibrate the sensor by analyzing proportional relationships using Excel.
• Students measure the electrical conductivity of water samples to investigate possible sources of pollutants using data visualized with digital tools.

21st century technical skills gained through this activity:

• Mechanical engineering
• Electrical engineering
• Software engineering
• Data science 

Scope and Sequence

See the Detailed Lesson Timeline for a more in-depth look at the lesson.

Part 1: Prior knowledge and vocabulary

• Students are introduced to the context of the lesson which places them in the role of a hydrologist monitoring water quality in a local watershed. Students answer questions related to lesson learning objectives as a pre-assessment.  Students are also introduced to the project’s working vocabulary.

Part 2: Analog data

• Students build an analog electrical conductivity (EC) sensor for dry materials. Students test a variety of dry materials with their EC sensor and classify them as conductors or insulators. Students then construct an analog EC sensor to test the conductivity of liquids. Students add small amounts of baking soda to their solution, changing the conductivity and impacting the brightness of an LED attached to the sensor.

Part 3: Digital data

• Students build and calibrate a digital EC sensor from stainless steel wire and a drinking straw. They connect their digital EC sensor to Excel for data visualization using a microcontroller. Students use a custom Excel worksheet and water samples prepared by their teacher to model a stream hydrologist collecting and analyzing pollution data. Students are also given the opportunity to collect and analyze water samples from their local watershed and visualize and store their data in Excel.

Part 4: Reflection

• Students  finalize any unfinished components of the student journal. Students complete and discuss the reflection questions in the Student Journal.