Water for Schools
Menu

Classroom activity Grade 8 Art & Music

Nitrogen as Resource and Pollutant: A Sturgeon Lake Diptych Studio

A grade 8 art activity where partners build a two-panel diptych showing a nutrient as both a crop resource and a pollutant that harms fish, with a short argument caption.

Objectives

  1. Students will design a two-panel diptych that contrasts a nutrient as a resource and as a pollutant.
  2. Students will write a short caption arguing how too much of the nutrient changes a lake and affects fish.
  3. Students will use color and composition so the two panels read as opposites at a glance.

Vocabulary

Dissolved oxygen
Dissolved oxygen is the oxygen gas mixed into water that fish and other underwater animals breathe. Cold, moving water holds more oxygen than warm, still water.

Also: diptych, nutrient, algae bloom, composition

Teacher overview

A diptych is a single artwork made of two panels meant to be read together. This is a partner studio activity for pairs, in which each pair builds a diptych about one nutrient, nitrogen, that plays two opposite roles in water. On the left panel the nutrient is a resource: it feeds crops and makes fields green. On the right panel the same nutrient, washed into a fictional lake called Sturgeon Lake in far larger amounts, becomes a pollutant that feeds an algae bloom, lowers the oxygen fish need, and drives fish from the water. The two panels require students to show one substance producing opposite outcomes, and the caption asks them to argue how the change in amount affects the lake's fish.

Activity Directions

  1. Introduce the idea with a plain statement: nitrogen is a nutrient plants need, yet the same nutrient in large amounts running off into a lake can harm it. Tell students they will show both sides of this one substance in a two-panel diptych.
  2. Explain the science students will picture. On farm fields, nitrogen fertilizer helps crops grow. When heavy rain washes extra nitrogen into a lake, it feeds a fast growth of algae called a bloom. When that algae dies and breaks down, the process uses up the dissolved oxygen in the water. Fish need oxygen above about 5 milligrams per liter, and when it falls below that, fish can die or leave.
  3. Pair students and give each pair one sheet divided into two panels and an index card for the caption.
  4. Left panel, the resource story (12 minutes): pairs design an image showing nitrogen as something useful, such as green crops in a field, using warm, healthy colors and an upward, growing composition.
  5. Right panel, the pollutant story (12 minutes): on the same sheet, pairs design the opposite outcome in Sturgeon Lake, such as a green-scummed surface and fish in trouble, using colors and a composition that clearly read as the reverse of the left panel.
  6. Caption (10 minutes): on the index card, each pair writes a three-to-five-sentence argument that answers one question: how does adding too much nitrogen change Sturgeon Lake, and what happens to its fish? The caption must name the algae bloom and the drop in oxygen as the links in the chain.
  7. Gallery walk (8 minutes): pairs post their diptychs. Students walk the gallery and, for each diptych, decide silently whether they could tell the two panels apart as opposites without reading the caption.
  8. The activity ends after the gallery walk; gather the class for the debrief.
  9. Debrief questions: "What is the chain of steps that connects extra nitrogen to fewer fish?" and "Which color or composition choices made the two panels read as opposites?"

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key

  1. Debrief question: "What is the chain of steps that connects extra nitrogen to fewer fish?" Answer: Extra nitrogen washes into the lake, which feeds a fast growth of algae called a bloom. The algae later dies and breaks down, and that decay uses up the dissolved oxygen in the water. With oxygen below the level fish need, fish die or leave, so the population drops. A strong answer names the bloom and the oxygen drop as the middle links, not just "pollution causes fewer fish."

  2. Debrief question: "Which color or composition choices made the two panels read as opposites?" Answer: Accept any specific, contrasting choices students actually used, such as warm healthy greens and an upward, growing layout on the resource panel against a dull or sickly green, a scummed surface, and a downward or crowded layout on the pollutant panel. The point is that the two panels use deliberately opposite visual signals so a viewer reads them as two sides of one substance.

Differentiation

Support

Provide a simple four-box cause-and-effect strip (extra nitrogen, algae bloom, oxygen drops, fish decline) that pairs can fill in before they design, so the argument chain is clear before the art begins. Offer a caption sentence frame.

Extension

Ask pairs to add a small third element bridging the two panels, such as a storm drain or a farm ditch, and to add one sentence to the caption explaining how a design choice on a farm could keep the resource from becoming a pollutant.

ELL supports

Pre-teach "nutrient," "bloom," and "oxygen" with quick sketches. Allow the caption to be built from labeled arrows between pictures first, then turned into sentences with a partner, and permit the debrief answers to be given orally.