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Model Nutrient Cycles 

7-12th Grade Science - Chemistry

Content Topics

  • Chemistry
  • Paleontology
  • Geology

Duration Two class periods (approximately 2 hours)

Objective: 

Students will model the cycling of nutrients through an environment, based on fossils from your county while learning about the water, carbon, nitrogen, and phosphorus cycles. They will use chemical reactions to demonstrate how nutrients get into the soil, end up in the ocean, and then become part of the long-term storage on Earth. At the end, they will learn about how tectonic processes and erosion and deposition can bring those nutrients back to Earth’s surface to repeat the cycle. Students will also watch permineralization and storage in bones to understand some of the long-term storage on land.

Overview and Purpose:

The purpose of this lab is to help students understand where carbon, phosphorus and nitrogen are stored, while including their transport through the water cycle. This model will also engage students in conversations about long-term and short-term storage processes.

Guiding Questions: 

  • Where are the elements important to life made and stored?
  • How do nutrients become bioavailable?
  • How are nutrients transported between the geosphere, hydrosphere, atmosphere, and biosphere?

Education Standards:

  • MS-ESS2-1 Develop a model to describe the cycling of Earth’s materials and the flow of energy that drives this process
  • MS-ESS2-4 Develop a model to describe the cycling of water through Earth’s systems driven by energy from the sun and the force of gravity
  • MS-ESS3-1 Construct a scientific explanation based on evidence for how the uneven distributions of Earth’s mineral, energy, and groundwater resources are the result of past and current geoscience processes
  • MS-LS2-3 Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem
  • HS-LS2-3 Construct and revise an explanation based on evidence for the cycling of matter and flow of energy in aerobic and anaerobic conditions
  • HS-LS2-4 Use mathematical representations to support claims for the cycling of matter and flow of energy among organisms in an ecosystem

Materials and Resources:

  • Large plastic tubs
  • Chalk
  • Seltzer water
  • Cold brew tea bags
  • Baking soda
  • Vinegar? 
  • Seashells
  • Table salt
  • Sand blast sand
  • Fish tank pebbles
  • Slopes (funnels 6.25”)
  • Sponges 
  • Lemon juice
  • Miniature cows, pigs, corn plants and pea plants and a representation of nitrogen-fixing bacteria, house.
  • Labels
  • Lab Worksheet

Local Resources:

Part 1 (50 Min)

Introduction/ Hook:

Students will begin by building their entire setup and adding substances to the soil and water. Students will crush chalk or Tums into their sand and fish tank pebbles, and add water to build up their slopes on the funnel. Tea will be added to the surface of the sand to represent plant matter. They will add baking soda and table salt to the water in the bottom of the tub (ocean) to represent salts in the ocean. They will add lemon juice to the water to represent urine (nitrogen) from cattle and other animals entering the soil. They will add “gray” water from a house to represent phosphorus added to water systems. Then, they will let the sponge represent a rain cloud and let the rain fall on the slope letting everything run into the ocean basin.

Primary Source Materials:

  • Fossils from plants, oceanic animals, and terrestrial animals
  • Fossils that glow
  • Coal
  • Clinker 
  • Limestone
  • Carbon sequestration plans

Presentation:

Earth’s Nutrient Cycles

  • Will include information about nutrient cycles
  • Macromolecules of life
  • Carbon sequestration
  • Coal mining and burning
  • Phosphorus and calcium carbonate mining


Activity Part I: Setting up Your Model

  1. Place the slopes into the tubs and add enough water to barely cover the bottom. The bottom, flat piece of the slope is the continental shelf where the water reaches the ocean. 
  2. Have students mix their chalk (crushed with rocks or a mortar and pestle, 3 sticks)  and fish tank pebbles into the sand provided (4 cups of sand per student). They can add water as needed to make the mixture stay put. 
  3. Have students place cows, pigs, and plants on their ground below the funnel at the base of the slope (where the farming and ranching is occurring). 
  4. Cut open a tea bag and place tea along the ground and in the river to represent plant matter from the mountain and surrounding farmland. 
  5. Give students the labels for the geosphere, hydrosphere, biosphere, and atmosphere and tell them to place the labels appropriately (on the outside of the plastic tub). Go around and check their labels. 
  6. Add two teaspoons of baking soda and three teaspoons of table salt to the ocean water. These represent the salts and carbonate ions in the ocean water. 
  7. Add a tablespoon of lemon juice to the large river to represent urine from cattle and other organisms entering the soil and then the waterways. Write any observations you have at this time in the data table. 
  8. Add one tablespoon of green water into the river system to represent gray water coming from industrial processes and houses carrying phosphorus. Place this water in the stream next to the building. This water represents phosphorus being added. Write any interesting observations.
  9. Take a wet sponge and wring water on the top of the slope until the river flows and particles start to move to the ocean. 
  10.  As the liquids run through, note how far the different sizes of particles travel into the ocean. Drop seashells into the ocean water and let everything settle. Write down any observations on the land and water in the data table. 
  11. The tubs can sit overnight. Place a couple toy bones in the ocean water. Fill a hollow toy bone or 3-D printed bone with the ocean water and set it aside to let the water evaporate away.

Part 2 (50 Min)

Activity Part II: Macromolecules and Nutrient Cycles

  1. Begin the Nutrient Cycles Slides presentation with the students. Go over the macromolecules of life with the students. (Earth’s Nutrient Cycles)
  2. Emphasize that all living things require all of the macromolecules. Then, give students the element labels and have them place elements next to the macromolecules that use those elements. 
  3. Next, give students the function, uses, and subunit labels to place on the chart under the macromolecules. 
  4. Check the student’s charts and have them refer back to the presentation to help with the chart. 
  5. Go through the nitrogen cycle with students.
  6. When you finish the nitrogen cycle, give students the nitrogen cycle labels and have them label all of the pieces for the nitrogen cycle on the model. These labels can go in the tub and outside the tub. 
  7. Go over the phosphorus cycle with the students. When you finish the phosphorus cycle, give students the phosphorus cycle labels and have them label all of the pieces for the phosphorus cycle. These labels can go in the tub and outside the tub.
  8. Show students the fluorescent/phosphorescent fossils and explain the types of environments they were found in and what that tells us about the past climate and phosphorus storage in the region.
  9. Go over the carbon cycle with the students. When you finish the carbon cycle, give students the carbon cycle labels and have them label all of the pieces for the carbon cycle. These labels can go in the tub and outside the tub.
  10. Finally, go over the water cycle. When you finish the water cycle, give students the water cycle labels and have them label all of the pieces for the water cycle. These labels can go in the tub and outside the tub.
  11. Go through the human impact on nutrient cycles with the students. Show the students samples of coal and limestone. Use leaves and the sands and seashells and bones to show students how coal and limestone form. Then, show them samples of limestone and coal with the fossils still in them. Show them clinker which is a lower quality form of coal that burned underground and took on the red colors. 
  12. Give students the final set of labels and label the plants and animals as short-term carbon, nitrogen, and phosphorus storage. The crystals inside the bones will be labeled long-term carbon and phosphorus storage, and the limestone in the bottom of the ocean will be labeled long-term carbon and phosphorus storage.
  13. Allow students to place lemon juice on a piece of limestone to show how acids release carbon dioxide gas. Explain that limestone exposed in the Hell Creek and Pierre Shale formations after millions of years of long-term storage is now releasing the carbon dioxide back into the air. But this happens when rocks become exposed due to erosion, the oceans become more acidic and dissolve limestone and seashells or there is acid rain on limestone formations, or we mine for fossil fuels like coal and oil and then burn them. (Here, students can learn about energy conversions from coal, burning sugar, photosynthesis, electricity, and CO2 pumping.)
  14. Students will fill out the worksheet provided to consolidate what they learned.