Chemistry · 9th Grade

Active learning ideas

Water Quality and Contaminants

Active learning works for this topic because water quality engages students emotionally and intellectually through real-world relevance. When students analyze actual data or trace contaminants to their sources, they see chemistry as a tool for solving public health problems, not just abstract equations.

• Common Core State Standards
• HS-ESS3-3
• HS-PS1-2

• 20–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Problem-Based Learning
• 40 min · Small Groups

Data Analysis: Reading Water Quality Reports

Provide groups with a consumer confidence report from a local water utility alongside EPA maximum contaminant levels. Students identify which contaminants are present, compare values to legal limits, and classify each as biological, chemical, or physical, then present findings and propose questions for further investigation.

Identify common chemical contaminants found in water sources.

Facilitation Tip

During the Data Analysis activity, circulate as students compare contaminant levels to EPA standards, asking them to justify whether each contaminant exceeds safe thresholds using the data tables.

What to look for

Provide students with a list of common water contaminants (e.g., lead, nitrates, chlorine, PFAS). Ask them to select two and write a brief explanation of their chemical properties and one associated health risk.

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Activity 02

• Case Study Analysis
• 45 min · Small Groups

Case Study Analysis: Flint Water Crisis Chemistry

Guide students through the chemistry of the Flint, Michigan water crisis, focusing on how lead leached from pipes due to corrosive water conditions. Students identify the chemical factors that increased corrosivity, then analyze what could have been done differently at each stage using their chemistry knowledge.

Explain the health risks associated with various water contaminants.

Facilitation Tip

For the Flint Water Crisis Case Study, assign roles so students analyze lead levels, pH changes, and corrosion chemistry from different stakeholders' perspectives.

What to look for

Pose the question: 'Why are some chemicals, like PFAS, considered 'forever chemicals' while others, like iron in hard water, are more easily managed?' Facilitate a discussion focusing on bond strength, reactivity, and environmental persistence.

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Activity 03

• Gallery Walk
• 35 min · Small Groups

Gallery Walk: Contaminant Chemistry Profiles

Post stations with profiles of different contaminants (lead, nitrates, PFAS, arsenic, microplastics), each showing molecular structure, source, health effects, and persistence data. Students rotate with a graphic organizer to compare chemical properties and identify which contaminants are most persistent and why.

Analyze the chemical properties that make certain substances persistent pollutants.

Facilitation Tip

In the Gallery Walk, place contaminant profiles at stations so students move between sources, chemical properties, and real-world consequences in a structured sequence.

What to look for

Students complete the sentence: 'A key chemical property that makes a substance a persistent pollutant is ______ because ______.' They should also list one example of a persistent pollutant.

• Understand
• Apply
• Analyze
• Create
• Relationship Skills
• Social Awareness

Activity 04

• Think-Pair-Share
• 20 min · Pairs

Think-Pair-Share: Why PFAS Is Difficult to Remove

Provide a brief reading on PFAS chemistry and ask students to identify the structural feature that makes PFAS resistant to environmental breakdown. Partners compare explanations and together write a two-sentence summary connecting C-F bond strength to the concept of environmental persistence.

Identify common chemical contaminants found in water sources.

Facilitation Tip

During the Think-Pair-Share on PFAS, provide a one-page summary of PFAS chemistry to ground student discussions before they address removal challenges.

What to look for

Provide students with a list of common water contaminants (e.g., lead, nitrates, chlorine, PFAS). Ask them to select two and write a brief explanation of their chemical properties and one associated health risk.

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

A few notes on teaching this unit

Teachers should anchor discussions in concrete data and local contexts to counter abstract fears about contaminants. Avoid overwhelming students with too many contaminants at once; focus on three to four key examples that demonstrate diverse chemical behaviors. Research shows students retain concepts better when they trace contaminants from source to sink and connect chemical properties to treatment methods.

Successful learning looks like students connecting chemical properties to contaminant behavior in water systems. They should confidently explain how solubility, pH, or bond strength determine treatment challenges and health risks. Evidence will show in their ability to interpret data, discuss case studies, and critique solutions.

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Watch Out for These Misconceptions

• During the Data Analysis activity, watch for students assuming that any detectable chemical in water is unsafe.

  Use the EPA's maximum contaminant levels table in this activity to explicitly teach that safety depends on concentration thresholds and regulatory standards, not just presence of a substance.

• During the Flint Water Crisis Case Study activity, watch for students believing that the water crisis was caused solely by one action or single contaminant.

  Use the timeline and chemical data in this case study to show how multiple factors—pH changes, corrosion, lead service lines, and delayed response—interacted to create the crisis, emphasizing systemic issues in water treatment.

• During the Gallery Walk activity, watch for students assuming contaminants come only from factories or industrial sites.

  Use the diverse contaminant profiles in this gallery to highlight how agricultural runoff, old pipes, septic systems, and everyday products contribute contaminants, making the issue multifaceted.

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Methods used in this brief

• Problem-Based Learning
• Case Study Analysis
• Gallery Walk
• Think-Pair-Share