Summary

In this lesson, students are presented with an environmental problem to solve using important concepts of chemistry, which involves a lake with deteriorating water quality. Students are provided with a map of the area, its history, a list of problems that are occurring at Lake Kamari, and water-quality data. They are challenged to determine the cause of the problems and come up with possible solutions. The lesson brings together elements of chemistry, biology, and Earth science.

Grade Level

Elementary school and Middle school

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

• 5-PS1-1: Develop a model to describe that matter is made of particles too small to be seen.
• 5-PS1-3: Make observations and measurements to identify materials based on their properties.
• 5-PS1-4: Conduct an investigation to determine whether the mixing of two or more substances results in new substances.
• 3-5-ETS1-1: Define a simple design problem reflecting a need or want that includes specified criteria for success and constraints on materials, time, or cost.
• 3-5-ETS1-2: Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.
• Scientific and Engineering Practices:
  • Asking Questions and Defining Problems
  • Analyzing and Interpreting Data
  • Planning and Carrying Out Investigations
  • Constructing Explanations and Designing Solutions
  • Engaging in Argument from Evidence
  • Obtaining, Evaluating, and Communicating Information
• Crosscutting Concepts:
  • Cause and Effect: Mechanism and Explanation
  • Systems and System Models
  • Energy and Matter: Flows, Cycles and Conservation
  • Stability and Change

Objectives

By the end of this lesson, students should be able to:

• Describe effects of acidic water on living and nonliving things.
• Identify sources of acidity in water.
• Describe ways to prevent acidification of water.
• Describe at least one way to reverse acidification of water.
• Describe at least one way to “live with” acidic lake water.
• Evaluate possible solutions to water pollution.

Chemistry Topics

This lesson supports students’ understanding of the following topics in chemistry:

• Chemical reactions
• Mixtures and solutions
• Acids

Time

Teacher Preparation: 30–60 minutes to prepare samples of water with various pH values.

Lesson:

• Engage: 30 minutes
• Explore/Explain 1: 60–90 minutes
• Explore/Explain 2: 15–20 minutes
• Explore/Explain 3: 45–60 minutes
• Explore/Explain 4: 45–60 minutes
• Explain: 45–60 minutes
• Elaborate: variable
• Evaluate: 10–30 minutes
  

Materials

Preparation:

• Plastic containers with lids (2 L to gallon size; quantity depends on the number of students)
• Tap water
• White distilled vinegar
• pH meter or litmus paper

Engage

For each student:

• Lake Kamari Information Pack (Map, Facts, Water Quality Report)
• Science Journal
• Explore Questions 1 and 2 (testing water)

Explore Questions 1 and 2 (testing water)

For each student:

• Goggles
• Apron
• Latex gloves
• Lake Kamari Information Pack
• Science Journal

For each group:

• Internet and other research materials
• “Samples” of water (see Preparation in Teacher Notes)
  • Lake water from 2009 (tap water with a pH of 6.5 –7)
  • Lake water from 2014 (tap water + vinegar to a pH of 5–5.5)
  • Optional: Rain water from 2009 (tap water + vinegar to a pH of 5.5–6)
  • Optional: Rain water from 2014 (tap water + vinegar to a pH of 5.5–6)
  • Water from the Kamar River (2014), where it empties into the Lake (tap water + vinegar to a pH of around 4)
• pH meter or litmus paper
  

Explore Question 3 (neutralizing water)

For each student:

• Goggles
• Apron
• Latex gloves
• Science Journal

For each group:

• Container of “lake water” (pH 5–5.5)
• Small cups
• Measuring spoons
• Measuring cup or graduated cylinder
• Stirring rod or spoon
• pH meter or litmus paper
• Sieve
• Magnet
• Paper towel
• Baking soda
• Antacid tablets
• Other safe substances that can be added to water:
  • Soap
  • Salt
  • Sand
  • Sugar
  • Carbonated water
  • Vinegar
  • Lemon juice

Explore Question 4 (testing effects of acidity on building materials)

For each student:

• Goggles
• Apron
• Latex gloves
• Science Journal
  

For each group:

• Internet
• Container of “lake water” (pH 5–5.5)
• Eyedropper
• Magnifying glass or hand lens
• Sample of chalk
• Sample of granite
• Sample of sandstone
• Samples of other building materials, such as steel, brick, concrete

Safety

Remind students not to drink the water samples. Although the samples they will be working with are not actually dangerous, students should model good lab practice by wearing goggles, aprons, and gloves when working with the acidic water samples.

Vocabulary Terms

• Acid
• Acidic
• Chemical reaction
• Neutral
• pH
• Water quality

Keywords

Environment, water quality, watershed, pollution, pH, acidity, neutralization, engineering, mitigation

Teacher Notes

Lesson Organization

This lesson is organized into four parts, each focused on a guiding question. For each part, students conduct research using the Lake Kamari Information Pack, hands-on activities, and library/Internet sources.

The fact sheet is comprehensive and includes more information than is needed to identify and address the main problem at Lake Kamari. To simplify the activity, you can remove some of the less important information, such as area, depth, and some details of the history. Be sure to leave in information about the location, water sources, and fact that a paper mill was built in 2010.

A variety of water quality data is included in the water-quality chart. To simplify the activity, you may wish to remove some of the surface water condition measurements. Be sure to keep in pH.

The guiding questions are as follows:

1. What is causing the problems that people and wildlife are experiencing at the lake? What is causing the acidity? Students use the data in the Information Pack along with other resources to discover that the problems at the lake are consistent with acidification of the lake water. They use the map and lake history to determine that the acidity is probably coming from the paper mill.
2. How could you stop acidic water from entering the lake (if that is part of the issue)? In this part of the lesson, students explore point sources of pollution. Students think about ways to stop acidic water from leaving the paper mill or from getting into the lake.
3. If you can’t prevent the water from becoming acidic in the first place, how could you make the water less acidic? In this part of the lesson, students explore neutralization reactions. Students experiment with adding various substances to the lake water to increase the pH.
   
4. If you can’t change the acidity of the water, what can you do to minimize the negative effects of the acidity? In this part of the lesson, students explore introduction of fish that can tolerate higher levels of acidity and test the reactivity of various building materials with acidic water.

Differentiation

As written, this lesson is relatively complex and is best suited for upper elementary or middle grades. However, it can be modified for lower levels. You should feel free to modify the scenario, questions, and instructions as needed for your class. The lesson can be as basic or as complex as you wish to make it. Suggestions for differentiating this lesson include:

• There are four exploratory questions to answer. The questions can be addressed sequentially as a multiday lesson. Alternatively, they can be addressed individually, as separate lessons. Questions 3 and 4 can be skipped, depending on the time available or the level of your students.
• As written, chemical reactions are mentioned but not discussed in detail. The lesson can be modified to include more discussion of the simple reactions involved.
• Questions can be handled superficially through discussion only, or more in-depth using the hands-on activities provided and with additional research.
• The activities in the lesson can be simplified by reducing the amount of data given in the water quality chart or the information given on the fact sheet to include only the most pertinent information (e.g., acidity, direct causes of acidity)
• More or fewer water samples can be provided to students. If needed, students can analyze just two samples: the lake water from 2009 and from 2014. Higher-level students can be given rain samples as well as lake and river samples to analyze.
• The activities can be modified for higher grades by changing some of the values in the Water Quality Report that would indicate other possible causes of the problems at the lake (e.g., decrease 2014 dissolved oxygen levels; increase 2014 ammonia levels). Rain samples can be modified to show an increase in acidity of rain water from 2009 to 2014.
• To make the activity more complex, include weather data for students to analyze. Drought can be another factor in acidification.
• Advanced students can assist in the preparation of the water solutions before the lesson.

Preparation

1. Revise the Lake Kamari Information Pack and Scenario (in Engage) as needed for your class.
2. Prepare “samples” of water for students to test.

There are a number of ways to make acidic solutions. Because of the variation in acidity of the components, preparation will require some trial and error. Approximate ratios are provided in the Notes column of the table below.

Tip: If your solution is too acidic, add baking soda to increase the pH.

Science Background

Water quality

Water quality is a serious issue affecting drinking and recreational water supplies around the world. In this lesson, students explore one specific property of water quality in detail—acidity. Acid rain and release of acidic water into waterways poses major problems to aquatic organisms as well as animals that rely on aquatic organisms for food. While some organisms can tolerate some acidity, in general the variety of organisms in and around a body of water decreases with increasing acidity. Acidic water is irritating to human skin and eyes. It reacts with rocks such as limestone, causing them to weather or break down quickly. Note that rain water is naturally slightly acidic.

Acidity is generally described in terms of pH. The pH scale runs from 0 to 14. Solutions with a pH of 7 are considered neutral, while those below 7 are acidic and those above 7 are basic. pH values can be measured using a pH meter, litmus paper, or various other indicators.

Chemical Reactions

In this lesson, students explore a number of simple chemical reactions.

• In Question 1, students determine the cause of various environmental problems at Lake Kamari. All of these problems are related to the acidic water (with human skin, with organ systems of animals, with building materials).
• In Question 2, students determine the cause of the acidity. In the scenario, a paper mill is polluting the Kamar River. The paper production process involves a number of chemical reactions. Paper mills emit wastewater that can include a variety of pollutants, some of which can cause acidity.
• In Question 3, students explore ways to neutralize an acidic solution, or make it less acidic. Students are provided with a variety of substances to mix with the acidic lake water. Baking soda (NaHCO₃), calcium carbonate (CaCO₃), and magnesium hydroxide (Mg(OH)₂) react with acids to neutralize acidity.
• In Question 4, students explore the reaction between acidic water and rocks and minerals. Acidic water reacts with calcium carbonate (CaCO₃) in limestone, causing it to break down. (Chalk is a very soft type of limestone that reacts quickly with acidic water.)

Additional Resources

Find out more about water quality and acidity:

• UNC Water and Sustainability
  
• USGS Water Quality Information
  
• EPA Acid Rain Experiments
  
• BBC Bitesize: Acids, Neutralization, and Salts
  
• Paper Making and Recycling
  
• Effects of Acid Rain