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Investigate Acid Rain

Lesson at a glance:

Students will investigate one possible threat to frogs and other amphibians by conducting an experiment about acid rain.

Relevant National Curriculum Standards and Benchmarks:

Standard: Understands how species depend on one another and on the environment for survival

Benchmark: Upper Elementary (Grades 3-5): Knows that the behavior of individual organisms is influenced by internal cues (e.g., hunger) and external cues (e.g., changes in the environment), and that humans and other organisms have senses that help them to detect these cues.
Benchmark: Upper Elementary (Grades 3-5): Knows that an organism's patterns of behavior are related to the nature of that organism's environment (e.g., kinds and numbers of other organisms present, availability of food and resources, physical characteristics of the environment).
Benchmark: Upper Elementary (Grades 3-5): Knows that changes in the environment can have different effects on different organisms (e.g., some organisms move in, others move out; some organisms survive and reproduce, others die).
Benchmark: Upper Elementary (Grades 3-5):Knows that all organisms (including humans) cause changes in their environments, and these changes can be beneficial or detrimental.
Benchmark: High School (Grades 9-12): Knows ways in which humans can modify ecosystems and cause irreversible effects (e.g., human population growth, technology, and consumption; human destruction of habitats through direct harvesting, pollution, and atmospheric changes)

Standard: Understands the nature of scientific inquiry

Benchmark: Primary (Grades K-2): Knows that learning can come from careful observations and simple experiments
Benchmark: Upper Elementary (Grades 3-5): Knows that scientific investigations involve asking and answering a question and comparing the answer to what scientists already know about the world.
Benchmark: Upper Elementary (Grades 3-5): Plans and conducts simple investigations (e.g., makes systematic observations, conducts simple experiments to answer questions)
Benchmark: Upper Elementary (Grades 3-5): Knows that good scientific explanations are based on evidence (observations) and scientific knowledge.
Benchmark: Middle School/Jr. High (Grades 6-8): Designs and conducts a scientific investigation (e.g., formulates questions, designs and executes investigations, interprets data, synthesizes evidence into explanations, proposes alternative explanations for observations, critiques explanations and procedures.
Benchmark: Middle School/Jr. High (Grades 6-8): Uses appropriate tools (including computer hardware and software) and techniques to gather, analyze, and interpret scientific data.
Benchmark: High School (Grades 9-12): Understands the use of hypotheses in science (e.g., selecting and narrowing the focus of data, determining additional data to be gathered; guiding the interpretation of data).
Benchmark: High School (Grades 9-12): Designs and conducts scientific investigations by formulating testable hypotheses, identifying and clarifying the method, controls, and variables; organizing and displaying data; revising methods and explanations; presenting the results; and receiving critical response from others.

These national standards and benchmarks are summarized at http://www.mcrel.org/standards-benchmarks/

Materials:

• A measuring cup
• Three small potted plants
• A bottle of vinegar or lemon juice
• Six 2-inch strips of masking tape
• A pen or marker
• Three 1-quart jars and two lids

Background:

One possible reason for the decline of some frog population is acid rain. Acid rain is formed when invisible gases are released into the air and mixed with rain clouds. Most of these gases come from businesses that burn large amounts of fossil fuels such as coal and oil. This is usually done to make electricity (produce power). Another source of harmful gases comes from driving cars that burn gasoline.

These gases combine with the moisture in the clouds and fall back to the ground not as clean rain but as acid rain. The acid in the water is harmful to plants, water systems, such as lakes and rivers, and animals such as salamanders and frogs. In eastern Europe, acid rain has actually destroyed forests. It also pollutes the water that humans and other animals drink.

Activity:

1. Label three 1-quart jars with the tape strips as follows: Weak Acid, Strong Acid and Plain Water
2. Label three potted plants with tape strips as follows: Weak Acid, Strong Acid and Plain Water.
3. Put ¼ cup vinegar or lemon juice in the jar labeled Weak Acid. Fill the jar to the top with tap water. Use this to water the plant labeled Weak Acid.
4. Add 1 cup of vinegar or lemon juice in the jar labeled Strong Acid. Fill the jar to the top with tap water. Use this to water the plant labeled Strong Acid.
5. Fill the jar labeled Plain Water to the top with tap water. Give this water only to the plant with the matching label. Do not put a lid on this jar.
6. Place the plants next to each other so they get the same amount of light. Cover both jars containing acid after you water the plants.
7. Don’t allow the plants to dry out. Test the soil daily, and water as needed. Water each plant only from the jar with the matching label. Give each plant the same amount of water. Check the appearance of the plants after one week. What do you notice about the plants?
8. Are they different in color?
9. How do you think acid rain might affect frogs?

Extensions:

• Use experiment to talk about scientific inquiry.
• Ask older students ways they could improve or expand on this simple experiment.
• Add replicates, different plant species, acid types.
• Ask students to make hypotheses.

Adapted from Educational Insights Eco Detective series.