Students learn about soil properties and the effect biochar—charcoal used as a soil amendment—has on three soil types, sand, loam and clay. They test the soils’ water retention capability before and after the addition of biochar. During the activity, student teams prepare soil mixtures, make observations (including microscopic examinations), compare soil properties, conduct water retention tests, take and record measurements, and analyze their observations and data. They see how the physical properties of soils—color, texture, and particle size—can be indicators of nutrient content and water retention capabilities to support plant growth. From their findings, they consider biochar’s potential benefits for environmental and agricultural applications, especially in conditions of drought and depleted soils. An activity lab sheet is provided to guide experimental data collection and analysis.

In this lesson, students are introduced to the types of renewable energy resources. They are involved in activities to help them understand the transformation of energy (solar, water and wind) into electricity. Students explore the different roles of engineers working in renewable energy fields.

Students build on their understanding and feel for flow rates, as gained from the associated Faucet Flow Rate activity, to estimate the flow rate of a local river. The objective is to be able to relate laboratory experiment results to the environment. They use the U.S. Geological Survey website (http://waterdata.usgs.gov/nwis/rt) to determine the actual flow rate data for their river, and compare their estimates to the actual flow rate. For this activity to be successful, choose a nearby river and take a field trip or show a video so students gain a visual feel for the flow of the nearby river.

Students learn how water is used to generate electricity. They investigate water's potential-to-kinetic energy transformation in hands-on activities about falling water and waterwheels. During the activities, they take measurements, calculate averages and graph results. Students also learn the history of the waterwheel and how engineers use water turbines in hydroelectric power plants today. They discover the advantages and disadvantages of hydroelectric power. In a literacy activity, students learn and write about an innovative new hydro-electrical power generation technology.

Students build a saltwater circuit, which is an electrical circuit that uses saltwater as part of the circuit. Students investigate the conductivity of saltwater, and develop an understanding of how the amount of salt in a solution impacts how much electrical current flows through the circuit. They learn about one real-world application of a saltwater circuit — as a desalination plant tool to test for the removal of salt from ocean water.

Student teams practice water quality analysis through turbidity measurement and coliform bacteria counts. They use information about water treatment processes to design prototype small-scale water treatment systems and test the influent (incoming) and effluent (outgoing) water to assess how well their prototypes produce safe water to prevent water-borne illnesses.

Students are introduced to the concepts of graywater and water reuse within households. They calculate the amount of used water a family generates in one day and use a model of home plumbing to find out how much graywater is produced in homes every day. They graph their results and discuss energy efficiency implications. Students are then challenged to find ways to reduce water use within the home.

Students use their understanding of projectile physics and fluid dynamics to find the water pressure in water guns. By measuring the range of the water jets, they are able to calculate the theoretical pressure. Students create graphs to analyze how the predicted pressure relates to the number of times they pump the water gun before shooting.

Students perform one of the first steps that environmental engineers do to determine water quality sampling and analysis. Student teams measure the electrical conductivity of four water samples (deionized water, purified water, school tap water and a salt-water solution) using teacher-made LED-conductivity testers and commercially available electrical conductivity meters. They use multimeters to also measure the resistance of the samples. They graph their collected data to see the relationship between the conductivity and resistance. Then, all students measure the conductivity of tap water samples brought to school from their homes; they organize and average their data by sub areas within their local school district to see if house location has any relationship to the water conductivity in their community.

Students build and use a very basic Coulter electric sensing zone particle counter to count an unknown number of particles in a sample of "paint" to determine if enough particles per ml of "paint" exist to meet a quality standard. In a lab experiment, student teams each build an apparatus and circuit, set up data acquisition equipment, make a salt-soap solution, test liquid flow in the apparatus, take data, and make graphs to count particles.

Engineers work in many fields associated with precipitation. Engineers study glaciers to better understand their dates of formation and current demise. They deal with issues of pollution transport and water yield, and they monitor reservoirs and dams to prevent flooding.

Over the course of three sessions, students act as agricultural engineers and learn about the sustainable pest control technique known as soil biosolarization in which organic waste is used to help eliminate pests during soil solarization instead of using toxic compounds like pesticides and fumigants. Student teams prepare seed starter pots using a source of microorganisms (soil or compost) and “organic waste” (such as oatmeal, a source of carbon for the microorganisms). They plant seeds (representing weed seeds) in the pots, add water and cover them with plastic wrap. At experiment end, students count the weed seedlings and assess the efficacy of the soil biosolarization technique in inactivating the weed seeds. An experiment-guiding handout and pre/post quizzes are provided.

Students learn about contamination and pollution, specifically in reference to soil in and around rivers. To start, groups use light sensors to take light reflection measurements of different colors of sand (dyed with various amounts of a liquid food dye), generating a set of "soil" calibration data. Then, they use a stream table with a simulated a river that has a scattering of "contaminated wells" represented by locations of unknown amounts of dye. They make visual observations and use light sensors again to take reflection measurements and refer to their earlier calibration data to determine the level of "contamination" (color dye) in each well. Acting as engineers, they determine if their measured data is comparable to visual observations. The small-scale simulated flowing river shows how contamination can spread.

In this lesson, students will explore the causes of water pollution and its effects on the environment through the use of models and scientific investigation. In the accompanying activities, they will investigate filtration and aeration processes as they are used for removing pollutants from water. Lastly, they will learn about the role of engineers in water treatment systems.

In this activity, students build a water filter with activated carbon, cotton and other materials to remove chocolate powder from water.

During this activity, students will learn how environmental engineers monitor water quality in resource use and design. They will employ environmental indicators to assess the water quality of a nearby stream. Students will make general observations of water quality as well as count the number of macroinvertabrates. They will then use the information they collected to create a scale to rate how good or bad the water quality of the stream. Finally, the class will compare their numbers and discuss and defend their results.

What happens when sugar and salt are added to water? Pour in sugar, shake in salt, and evaporate water to see the effects on concentration and conductivity. Zoom in to see how different sugar and salt compounds dissolve. Zoom in again to explore the role of water.

Students are introduced to superhydrophobic surfaces and the "lotus effect." Water spilled on a superhydrophobic surface does not wet the surface, but simply rolls off. Additionally, as water moves across the superhydrophobic surface, it picks up and carries away any foreign material, such as dust or dirt. Students learn how plants create and use superhydrophobic surfaces in nature and how engineers have created human-made products that mimic the properties of these natural surfaces. They also learn about the tendency of all superhydrophobic surfaces to develop water droplets that do not roll off the surface but become "pinned" under certain conditions, such as water droplets formed from condensation. They see how the introduction of mechanical energy can "unpin" these water droplets and restore the desirable properties of the superhydrophobic surface.

Surface tension accounts for many of the interesting properties we associate with water. By learning about surface tension and adhesive forces, students learn why liquid jets of water break into droplets rather than staying in a continuous stream. Through hands-on activities, students learn how the combination of adhesive forces and cohesive forces cause capillary motion. They study different effects of capillary motion and use capillary motion to measure surface tension. Students explore the phenomena of wetting and hydrophobic and hydrophilic surfaces and see how water's behavior changes when a surface is treated with different coatings. A lotus leaf is a natural example of a superhydrophobic surface, with its water-repellent, self-cleaning characteristics. Students examine the lotus effect on natural leaves and human-made superhydrophobic surfaces, and explore how the lotus leaf repels dewy water through vibration. See the Unit Overview section for details on each lesson in this unit.

Students are presented with the question: "Why does a liquid jet break up into droplets?" and introduced to its importance in inkjet printers. A discussion of cohesive forces and surface tension is included, as well as surface acting agents (surfactants) and their ability to weaken the surface tension of water. Students observe the effects of surface tension using common household materials. Finally, students return to the original question through a homework assignment that helps them relate surface tension and surface area to the creation of water droplets from a liquid jet.