Learn, Protect, and Promote Water!
6 - 8
In this lesson students learn about water sources, water pollution, and water protection. Students participate in an activity where they demonstrate the water cycle and see the potential for our water supply to become contaminated. Grades 6-8
30 - 45 minutes
best management practices: methods that can improve efficiency, optimize resources, and prevent or help reduce pollution
evaporation: the changing of a liquid into a gas
groundwater: precipitation that has infiltrated through soil, rock, and gravel in the ground
hydrologic cycle: a sequence of conditions where water moves through the atmosphere through precipitation, evaporation, and transpiration
non point source: nutrient pollution that results from runoff and enters surface, ground water, and the oceans from widespread and distant activities
point source pollution: pollution from a specific and identifiable source
precipitation: moisture in the form of rain, snow, sleet, or hail that falls to the ground
transpiration: the process by which plants release water vapor back into the atmosphere through their stomata
water table: The level in the ground which is saturated with water
Did You Know? (Ag Facts)
- Agriculture accounts for approximately 80% of the United States' consumptive water use.1
- Although agriculture accounts for a large portion of our water supply, large-scale farming could not provide food for the world's large populations without the irrigation of crop fields.2
- Irrigation has been around for as long as humans have been cultivating plants.2
Background Agricultural Connections
The hydrologic cycle, more commonly known as the water cycle, is a process where water is continually moving around the earth through precipitation, evaporation, and transpiration.
Precipitation is water in any form that falls from the sky. Evaporation is when water changes from a liquid to a gas after being heated by the sun. Transpiration is when water changes from a liquid to a gas after being absorbed through plant roots and then entering the atmosphere through the leaves.
Groundwater is water found underground in the cracks and spaces in soil and rock. Precipitation can help to increase groundwater levels if the precipitation is able to infiltrate deep enough through soil, rock, and gravel in the ground. Groundwater reaches aquifers, which is the saturated zone of the soil, rock, and gravel in the ground. Wells are drilled into aquifers to access water. The top of the aquifer, where the saturated zone meets the unsaturated zone, is called the water table.
Groundwater aquifers also serve to supply water to streams and other surface water. If not for groundwater, streams would dry up during the driest part of summer when it may not rain for weeks. In urban areas, groundwater recharge is reduced due to pavement, roofs, and other impervious surfaces.
On Earth, only 1 percent of water can be used for drinking. Additionally, groundwater is used for industry, mining, and agricultural purposes.
Water can become contaminated by both point source pollution, which is pollution from a specific and identifiable source, and non point source pollution, which is pollution from a less identifiable source, often spread over several areas, and can be mobilized by rainfall or snowmelt.
Point source pollution examples include:
- Factory waste from a pipe
- Discharge from manufacturing plant
- Waste water treatment facility outfall
Non-point source pollution examples include:
- Fertilizer in garden
- Dog waste in yard
- Motor oil residue on roads
In addition to other pollutants, pesticides, if not used appropriately, can contaminate both surface water and groundwater. The contamination can be effected by the weather, environment, soil conditions, and human activities. For example, sandy soil has larger soil particles and is more prone to pesticide leaching, which occurs when a pesticide moves through the soil to reach groundwater. Certain characteristics that make a pesticide more prone to leaching include:
- High solubility, meaning the pesticide can easily move in water
- Low adsorption, meaning the pesticide does not easily bind to the soil particles
- Persistent, meaning the pesticide does not easily break down in the environment
Point source pollution examples from pesticides include:
- Improper disposal of pesticide containers and pesticides, such as dumping excess pesticides down storm sewers and other locations.
- Pesticide use in vulnerable areas such as sandy soil, sinkholes, and shallow groundwater.
- Pesticides spills at mixing, loading, and equipment clean-up sites.
- Pesticide use around wells or other known water sources.
- Back-siphoning of pesticides into water sources.
- Any way that pesticides are not mixed, used, stored, and disposed of according to label directions.
Non-point source pollution from pesticides includes pesticides moving from large areas into water or groundwater, like what might occur after a rainfall, such as if pesticides are applied to fields and lawns prior to rainfall.
Best management practices (BMPs) are methods that can improve efficiency, optimize resources, and can prevent or help reduce pollution. If applying pesticides, BMPs should be used, which promote environmental stewardship and help prevent pesticide contamination of water. Best management practices with pesticides around water include:
- Determine need to use pesticide products and perform spot treatments when possible.
- Apply pesticides according to the label directions.
- Identify vulnerable areas such as sandy soil, sinkholes, wells, and shallow groundwater.
- Secure storage areas to prevent unintentional chemical exposure.
- Ensure chemicals are tightly closed and monitor for tears to prevent spills or leaks.
- Maintain a 100 foot buffer zone around wells, streams, rivers, and other known water sources when mixing, loading, and applying pesticides.
- Avoid back-siphoning of pesticides.
- Incorporate pesticides into the soil to reduce runoff.
- Have buffer strips to catch sediment and help slow runoff movement.
- Monitor weather to properly time pesticide applications.
- Regularly calibrate equipment.
- Handle pesticides and equipment safely.
- Seek assistance with any questions from Extension Educators and Department of Agriculture affiliates.
Other best management practices to help prevent water contamination include:
- Reduce or eliminate fertilizer use.
- Prevent chemicals from leaking.
- Pick up trash and animal waste.
- Be aware of oil residues from vehicles.
Interest Approach - Engagement
- As a class, or in smaller groups have students take turns sharing a response to the questions listed below. Each student should think of a response that has not already been shared. If everyone in the group answers, continue for a second round of sharing. Once students begin running out of responses, see if each group as a team can think of even more responses.
- How do I use water in my daily life?
- Who or what needs water?
- Tip: As students begin running out of ideas, give prompts such as, "Do farmers need water to produce our food? Is water necessary to process our food (clean, cook, and package it after it leaves the farm) and to keep restaurants clean and safe from foodborne illness? etc."
- Optional Adaptation: Another way to facilitate this activity is to have students write down responses as a group in a certain amount of time, such as sixty seconds. Have students share and compare responses. For a friendly competition, see which group comes up with the most unique responses
- Discuss and summarize the information found in the Background Agricultural Connections portion of the lesson. Inform students that they will be learning about the importance of water and how we can protect our water supply.
Activity 1: Groundwater Recharge, Pollution, and Protection
- Print and cut the Water Pollution Scenario Cards.
- Print the Mini Posters.
- Hang or place the "Clouds" sign at the front of the room or learning space. In the following order, display the "Plants," "Ground," and "Stream" signs several feet away from each other and several feet down from the "Clouds" sign, such as in the middle of the room. The "Aquifer" sign should be placed on the opposite end of the room or space from the "Clouds" sign, several feet down from the "Plants," "Ground," and "Stream" signs.
- Explain to students that groundwater is a very important resource. As a class they will soon be demonstrating the hydrologic cycle and groundwater recharge. They will serve as the "water" that moves through the hydrologic cycle and provides nutrients to plants, recharges groundwater, and supplies aquifers.
- Explain to learners that Pennsylvania [or insert your state's statistics here] gets 41 inches of precipitation, on average. Of that precipitation, approximately 50 percent will evaporate or transpire from plants, 30 percent will go to infiltrate through the soil and recharge groundwater, and 20 percent will land on the ground and runoff into streams.
- Ask for 20 volunteers. Assign the following number of students in respective roles: 10 students will represent evaporation and transpiration, 6 students represent groundwater recharge, and 4 students will represent runoff into a stream. Once roles are assigned, have the 20 students come to the front of the room and stand by the "Clouds" sign.
- Teach students that approximately 50 percent of the precipitation will evaporate or transpire from plants. Have 10 students leave the "Clouds" sign, representing precipitation, and move to the "Plants" sign.
- Teach students that 30 percent of the precipitation will infiltrate through the soil and recharge groundwater. Have 6 students leave the "Clouds" sign, representing precipitation, and move to the "Ground" sign. Have the students step over the Ground sign, representing how precipitation infiltrates into the ground. Have half (3 of the 6) of the students move and stand next to the "Aquifer" sign, demonstrating how groundwater fills aquifers. Have the other 3 move towards the "Stream" sign, (still below the "Ground" sign,) but forming a horizontal line to replicate how the groundwater feeds surface water like the stream.
- Next, teach students that 20 percent of the precipitation will land on the ground and runoff into streams. Have the 4 remaining students leave the "Clouds" sign, representing precipitation, and move towards the "Ground" sign. Once they reach the "Ground" sign, the students should not step over the sign, but should move horizontally across to the Stream sign, demonstrating how the precipitation becomes runoff and feeds into surface water, such as streams and lakes.
- Now that all students have moved away from the cloud, Instruct the group of 10 students standing at the "Plants" sign to move back to the "Clouds" sign, demonstrating how water will evaporate (change from a liquid to a gas from being heated by the sun) or transpire (change from a liquid to a gas from being absorbed through plant roots and going out through leaves) as part of the hydrologic cycle.
- Explain that groundwater recharge happens primarily in the spring and fall. In the winter, soil is often frozen. In the summer, plants are growing.
- A Step Further: Instead of assigning students to groups, ask for volunteers and then have the students determine the numbers for evaporation and transpiration, the groundwater recharge, and the runoff into streams using the given percentages. Or, have the students represent certain inches of precipitation and allow them to determine where the water will move. Example: Each student represents 4 inches of precipitation. To replicate the movement of 40 inches of precipitation, 5 students would move to the Plants sign, 3 to the Ground sign for groundwater recharge, and 2 would be the runoff for streams.
- Have the students remain in the same positions near the "Stream," "Groundwater," "Aquifer" and "Clouds" signs. Select an additional 4 students. These students will now be representing either a "Point Source Pollution" or a "Non point Source Pollution." Distribute one Water Pollution Scenario Card to each of the 4 students as well as the corresponding Groundwater Mini Poster.
- Ask the 4 students to read the instructions on their scenario card and instruct the rest of the group to remain in their current position unless prompted.
- Note: The scenario card instructions tell the student to read the instructions, perform the action when prompted by the instructor, and then share the talking points when prompted by the instructor.
- Instruct Person #1 and Person #2 to perform the action listed on their scenario card.
- Instruct Person #3 and Person #4 to perform the action listed on their scenario card. Once Person #3 is positioned near the "Plants" sign and Person #4 is positioned near the "Ground" sign, say “It’s Raining.” Instruct the students near the "Cloud" sign, who are serving as precipitation, to move, encouraging some to move towards the "Plants" sign and others to move towards the "Ground" sign. Person #3 and Person #4 have an additional action step on their scenario card to move once the precipitation reaches them. Instruct the precipitation students to either stop once they have reached the signs or, take it a step further, with having the students at the "Ground" sign to either infiltrate towards the "Aquifer" sign or runoff to the "Stream" sign.
- Ask the students about their observation of the pollution and which was point source or non point source pollution. Have Person #1, Person #2, Person #3, and Person #4 read the Talking Points on their scenario cards. Have students propose solutions to protect water sources, such as avoiding applying fertilizer or chemicals near expected rainfall events and ensuring that oil in motor vehicles is not leaking. More water protection solutions will be discussed in the next section.
Activity 2: Water Protection
- Discuss and summarize with your students the information found in the "Water Protection" section of the Background Agricultural Connections.
- Reference the 4 pollutants students learned about in Activity 1. Assign students to research and explore best management practices to help prevent water contamination. Examples include:
- Pollutant – Pesticide Backpack Sprayer Spill
- Best Management Practice (BMP) – Handle equipment safely.
- Pollutant – Fertilizer or Chemical Application
- Best Management Practice (BMP) – Determine need to even use pesticide products and perform spot treatments when possible. Monitor weather to properly time applications.
- Pollutant – Oil Residue on Road
- Best Management Practice (BMP) – Prevent leaking. Be aware of oil residues from vehicles.
- Pollutant – Pesticide Backpack Sprayer Spill
- Encourage students to identify areas around their home which are near or connected to water, such as storm sewers, well heads, streams, and others. Ask students about potential contaminants near these areas and if there are best management practices to reduce pollution.
Concept Elaboration and Evaluation
After conducting these activities, review and summarize the following key concepts:
- Water cycles through the atmosphere as a liquid, solid, or gas. This is known as the water cycle.
- Water is an important natural resource. Water supply is necessary and critical to produce our food.
- Water is a limited natural resource that needs to be managed properly and protected from pollution, damage, and waste.
- The use of "Best Management Practices" helps farmers and ranchers use water more efficiently as they produce our food.
http://extension.psu.edu/pests/pesticide-education/educators/ag-and-science-teachers/classroom-demonstrations-and-lessons/learn-protect-promote-waterPenn State Pesticide Education Program
Assign students to research specific examples and news articles that share about water contamination and the effects on the society. Allow students to share findings with a group.
Suggested Companion Resources
Penn State Pesticide Education Program