Environmental Monitoring

Background Information for Teachers

Human activity can impact the environment in a variety of ways, ranging from air or water pollution to the destruction of animal habitats. This lesson plan will allow your students to explore how some of these impacts can be measured electronically using the parts in the Electronic Sensors Kit. You can decide whether you would like your students to choose from the following suggested topics, think of their own topic, or focus on a single activity for the entire class. Links to related Science Buddies project ideas provide more background information about each topic.

• Light pollution/air quality: the kit contains a light sensor called a photoresistor. A photoresistor is a type of resistor whose resistance depends on light. This resistance can be measured with a multimeter and used to determine the brightness of a light source like in the projects How Does the Intensity of Light Change with Distance? or How Bright Is Your Glow Stick? Measure It!. You can measure how airborne particulate matter (smog, smoke, etc.) affects the light sensor reading, or how artificial lighting affects the light sensor reading outdoors at night. How does human activity impact light levels? How does this change in light affect plant and animal life?
• Water quality: you can also use the light sensor to measure water quality. How much light water absorbs depends on its color (darker water will absorb more light). The projects How Do You Take Your Tea? Make a Simple Electronic Device to Measure the Strength of Tea, How Blue is Your Sports Drink? and Adsorption: Dyeing Fabrics with Kool-Aid all make use of this fact. Water with suspended particles will scatter more light, as shown in How Flocculation Cleans Up Drinking Water. You can even use chemical reactions to cause water's color to change based on its pH, as shown in Get Energized with Cellular Respiration! and Dealing with Diabetes: The Road to Developing an Artificial Pancreas. Can your students use this information to measure water samples from a classroom aquarium or a local body of water? How does human activity affect the water quality?
• Conductivity meter: the chemical makeup and moisture content of a material can influence its electrical conductivity. The project Electrolyte Challenge: Orange Juice Vs. Sports Drink explores this phenomena with sports drinks and electrolytes, but you could do this experiment with wet soil instead. How does the soil's moisture content affect its conductivity? How does human activity like deforestation or irrigation affect soil moisture, and what effect does this have on plant and animal life?
• Water level detector: a circuit can be used to detect the presence (or absence) of water, as shown in Green Technology: Build an Electronic Soil Moisture Sensor to Conserve Water. This can be useful in a house, for example to detect an overflowing sink or a flooding basement. What about monitoring water levels in the environment? For example, detecting whether a pond has dried up, a reservoir is full, or a river has overflowed its banks? How does human water consumption affect water levels in the environment?

This is a very open-ended lesson. While there are specific instructions for building each circuit, how they use the circuit will be up to the students. Depending on your students' prior knowledge, you will need to decide what material you cover in class and/or what you assign as background reading material.

Additional Background Links

• How to Use a Multimeter, Science Buddies
• How to Use a Breadboard for Electronics and Circuits, Science Buddies
• Electricity, Magnetism & Electromagnetism Tutorial: Current Electricity, Science Buddies

Prep Work (1 hour)

Recommended: build and test the following three circuits yourself. This will help you understand how the circuits work and aid you when helping students troubleshoot their own circuits.

• The light sensor circuit from How Blue is Your Sports Drink?. The example project uses sports drinks, but can easily be adapted to use samples of dirty water instead.
• The conductivity meter from Electrolyte Challenge: Orange Juice Vs. Sports Drink. Use wet dirt instead of sports drinks. Instead of wrapping a copper wire around a straw to make a probe, wrap two popsicle sticks in aluminum foil. These will be easier to push into dirt.
• The moisture detector from Green Technology: Build an Electronic Soil Moisture Sensor to Conserve Water. Instead of using wet dirt, use a container of water. This circuit is binary (it detects the presence or absence of any moisture), so it works best to detect a rising or falling water level. The conductivity meter circuit provides a continuous reading, so it is better suited to evaluate soil moisture.

Engage (30 minutes)

1. Start the lesson with a general discussion about if and how human activity impacts the environment. Optionally, you could give a homework assignment for students to look up an article about human impact on the environment, and write a brief summary about the article for the next class period.

   Does human activity impact the environment? If so, how?

   Human activity impacts the environment in many ways and at different scales. For example, a factory dumping waste can pollute a local water supply, and large-scale burning of fossil fuels can cause climate change at a global level. There are many other examples (too numerous to list here).

2. Discuss how we can quantitatively measure our impact on the environment.

   Pick a specific way that human activity impacts the environment. How can we quantitatively measure that impact? What tools could we use to take the measurements?

   Again, there are many possible answers here. For example, one way to monitor climate change is by measuring temperatures at different locations around the globe and comparing them over long periods of time. We take these measurements with thermometers.

3. Introduce the Electronic Sensors Kit and the measurements that can be taken using the parts in the kit. Explain that students are limited to the parts in the kit, so some measurements they discussed previously may not be possible (for example, the kit does not contain a thermometer). You will need to decide exactly what information you present to your students here, based on the information in the Teacher Background section, but here is a brief overview:
   1. The kit contains a light sensor. The light sensor can be used in a variety of ways, for example to detect ambient light, to measure how much light is reflected off a surface, how much light is transmitted through (or refracted by) a liquid, etc.
   2. The kit can be used to measure how electrically conductive something is. Different factors can affect a material's electrical conductivity, for example the salt content of water or the moisture content of soil.
   3. The kit can be used to light an LED to indicate the presence or absence of water, like a puddle on the floor or a rising level in a lake.
4. Explain that students will now do a group project using the kit. Their goal is to design and build a circuit that can monitor something in the environment. They will collect data with their sensor and give a presentation to the class about how information from their sensor can provide feedback to humans about how our behavior impacts the environment. Pass out the grading rubric so students know what is expected of them.

Explore (4-6 hours)

1. Optional: if they have never used them before, introduce your students to breadboards and multimeters. Have each group complete the following activities, as shown in the printable circuit reference:
   1. Connect the multimeter to the photoresistor, and measure its resistance as light levels change (page 1).
   2. Build a basic LED circuit on a breadboard (page 2).
2. Brainstorm: in groups, students should decide what environmental variable they want to measure, and think about how human activity impacts this variable. You can decide whether to give them a list of possibilities or let them come up with their own ideas. If they come up with their own ideas, each group should briefly run their idea by the teacher to make sure it is feasible using the parts in the kit. For example, a group might decide that they want to measure the turbidity of water (the amount of suspended solid particles in the water).
3. Background reading: assign background reading based on what the students want to measure. They should learn about the quantity they want to measure and how it can be measured with a circuit. Note that while some Science Buddies projects may provide useful background information (Table 1), students might also need to do their own research. For example, a group that wants to measure water turbidity should read the project How Flocculation Cleans Up Drinking Water. This project explains that turbidity can be measured by aiming an LED at a sample of water, using a photoresistor to detect how much light is refracted by the water, and using a multimeter to measure the photoresistor's resistance.

4. Circuit design:  students should design their circuits, taking into account any criteria they think are necessary to make their circuit a functional measurement tool. Note that while most of the Science Buddies projects in Table 1 will show students how to connect the multimeter and/or build the circuit on a breadboard, there are other factors to consider. For example, for the turbidity meter:
   1. The photoresistor is heavily influenced by ambient light. How will they shield the circuit from ambient light? Do they want to use the circuit indoors? If so, how do light levels in the room change throughout the day, and how can that be controlled? Or, do they want to build a portable device that they can take to a nearby body of water? If so, can they build an opaque box for the circuit to protect it from sunlight?
   2. The amount of light that hits the photoresistor depends on the relative positions of the photoresistor and LED. The photoresistor and LED both have long, skinny legs that are easily bumped and bent when sitting in a breadboard. How will they make sure the photoresistor and LED stay in place when putting water samples in the circuit or moving it around?
   3. Circuits are not waterproof! How can they protect their circuit from spills when handling water samples?
   4. Once everything is connected, it can be difficult to move the circuit around with multimeter probes and battery leads dangling everywhere. Can they make the circuit less "messy" by taping down all the loose wires?
   5. Note that all the design considerations above are related. Ultimately, can they build a waterproof, portable enclosure for their circuit that allows them to reliably take repeatable measurements?
5. Circuit prototyping: once they have a plan, students should build and test a prototype of their circuit. This is where a lot of multimeter and breadboard troubleshooting might come into play ("our LED doesn't light up," "our multimeter's screen always displays zero," etc.). For help, you can refer to How to Use a Multimeter, How to Use a Breadboard for Electronics and Circuits, and (when available), the FAQs for the individual projects listed in Table 1. For the turbidity meter, students would want to confirm that they can get a resistance reading on their multimeter, and that this reading is lower for muddy water than it is for clear water (more light is scattered by the muddy water, so more light hits the photoresistor, causing its resistance to drop).
6. Calibration: students should understand how their circuit's input (in this example, a vial of muddy water) corresponds to the circuit's output (a resistance reading on a multimeter), and create a calibration curve if possible. This process is described for the turbidity meter in the "Calibrating Your Turbidity Meter" section of the procedure in How Flocculation Cleans Up Drinking Water. Note that, depending on which project the students selected, it might not be possible to create a calibration curve in this manner. For example, the water detector circuit is binary (it only turns an LED on or off, it does not give a continuous reading).
7. Data collection: if possible, students should collect real-world data using their sensor. For example, they could collect water from a nearby body of water after the weather has been clear for a few days, and after a rainy day.
8. Analysis: how does human activity impact their measurements? How could feedback from their sensor help us alter our behavior? For example, stormwater runoff from a nearby parking lot with poor drainage, or excessive erosion due to deforestation, could cause a large amount of sediment to be carried into a stream, increasing the water's turbidity. Measurements from turbidity meters over time could tell us whether a new stormwater management plan is effective.

Reflect (1 hour)

Each group should prepare a presentation to the class about their sensor that covers what the sensor measures, how it works, what they considered when designing it, the data they collected, and how information from the sensor can help us change our behavior. More information is provided in the example grading rubric.

End the lesson with a class-wide discussion about which of the devices might be useful in their local community, how the data could be acted on by the community, and what the long term affects of those actions might be on the ecosystem.

Assess

Evaluate student mastery of the objectives through oral or video presentations using this grading rubric.

Make Career Connections

Discussing or reading about these careers can help students make important connections between the in-class lesson and STEM job opportunities in the real world.

Environmental Scientist

Add Favorite Remove Favorite More Menu

• Read More

Career Profile

Environmental scientists study the environment and how things like deforestation and pollution affect human, plant, and animal life. If you enjoyed learning about how we can measure things in the environment and use that information to have a positive impact, consider learning more about environmental science. Read more

Electrical & Electronics Engineer

Add Favorite Remove Favorite More Menu

• Read More

Career Profile

Electrical engineers design the circuits that go inside the electronic gadgets we use every day like cell phones and video game consoles. If you enjoyed working with wires, breadboards, and multimeters, and would like to learn more about building circuits, you should read more about electrical engineering. Read more

Lesson Plan Variations

• You can purchase additional electronic components that are compatible with the Electronic Sensors Kit, for example a temperature sensor. Use add-on components to expand the breadth of environmental monitoring devices students can build.
• Instead of recording data manually with a multimeter, use an Arduino or a Raspberry Pi to automatically log data from your sensor. You can build a proof-of-concept device to use in the classroom, or even one that can collect data outdoors. There are many examples online of solar-powered weather/environmental monitoring stations made with Arduino, Raspberry Pi, or similar devices.