Initial Publication Date: September 5, 2024

Unit 3: Destiny Density

Summary:

Unit 3 introduces students to density through the cross-cutting concept lenses of patterns and structure and function across the gas, liquid, and solid components of our planet. Students investigate density, buoyancy, how fluids' behavior changes under different compositions (matter) and conditions (states of matter), and examine the role of density in fluids and fluid flow. Students will measure, calculate and compare the densities of different materials as well as construct and utilize models to examine the behavior of density differences of fluids in nature. Through these hands-on investigations and experiments, students use the knowledge they gain throughout the unit to explain structure and dynamic processes occurring in the natural world (e.g. weather patterns, atmospheric inversions, ocean circulation, plate tectonics). The unit culminates with students designing an NGSS lesson plan for their future classroom that focuses on one aspect of this unit using a scientific investigation.

The content and materials for this unit all connect to a central motivating question about the dynamic Earth system, from outer atmosphere to inner core. The motivating question prompts students to think about how, in order to identify and distinguish the different layers that make up the atmosphere, ocean, and Earth's interior, we must make observations from the invisible properties of temperature, pressure, and density.

Unit 3 follows a similar format to other units with students completing approximately weekly reflections about their learning for each specific subject and science journals for their lab activities. Students also practice their quantitative skills by collecting, graphing, and interpreting their own data, including applying proportionality of physical properties to natural systems and using simple standard deviation to evaluate experimental accuracy.

Most of these materials work well as standalone experiences if the entire unit cannot be completed and this unit is written with several extension labs and activities identified for classes that do not have lab sections. All extension activities are designed as deeper explorations of the prior unit materials.

Motivating question:

How do the invisible properties of density, pressure, and temperature, serve to structure the Earth, ocean, and atmosphere upon which we depend and live?

Time for this Unit:

This unit is designed to take about four weeks of class time (one third of a typical semester course). If all units are completed without any of the extension activities, then plan for 13-15.5 hours of class time. Extension activities and labs add an additional 4.5 hours of class time. Materials that can be skipped without loss of continuity are noted throughout.

Overview:

Throughout Unit 3, all activities use the theme of crosscutting concepts to build students' understanding of density and the role of density in Earth's dynamic systems. Students work through labs, discussions, and other class activities by making observations (including observations of "unobservable" things), asking questions and making hypotheses; collecting and analyzing data; and designing and using models before a final unit synthesis with the summative assignment of creating a NGSS lesson plan for a density-related activity.

  • Unit 3.1 How can we observe the unobservable? (75 min + 60 min extension lab/activity) Matter is made of atoms, but we cannot see them. How can we observe the "unobservable"? Students will use observations of the changing behavior of objects to make interpretations about the structure of atoms and practice "observing the unobservable". In the accompanying tape extension activity students will collect data from the interaction of objects to make interpretations about the structure of atoms and practice "observing the unobservable".
  • Unit 3.2: Why are there layers of the atmosphere? (120 min + 20 min extension lab/activity) We know the atmosphere is composed of gases and has a layered structure, yet these properties are invisible to the naked eye. Building on the idea of observing the unobservable, students will investigate air pressure, temperature gradient, and apply these concepts to explain natural phenomena.
  • Unit 3.3: What causes ocean stratification? (145 min + 50-80 min extension lab/activity) Students will use real world data to investigate the physical stratification of the ocean, measure the density of various fluids, construct and experiment with a physical model of the ocean's layers, and compare the relative scale of the real world data with the properties of the model.
  • Unit 3.4 (extension): What can we learn by mapping sea surface data? (140 min extension lab/activity) What can we infer from mapping sea surface temperature and sea surface elevation? Students will use satellite data to make observations and interpretations about ocean circulation in the North Atlantic. Students will also explore how to communicate data with art, like the climate scientist and artist Jill Pelto. This unit is based on activities developed by the European Space Agency and Jill Pelto via Science Friday. This extension unit and activities are designed to give opportunities for students to explore the course content more deeply if there is sufficient time, but classes that are short on time can skip these with no loss of continuity.
  • Unit 3.5: How do the densities of Earth materials relate to the layers of the Earth? (165 min) How do we measure the density of Earth materials? Students measure, calculate, and compare material densities while using models to explore fluid density variations.
  • Unit 3.6: Why do plates "tectonic"? (140 min) Why do plates "tectonic"? Students will apply their understanding of density and mechanical behavior of Earth's materials to design and build a model with which they can experiment with (and observe) plate boundary interactions.
  • Unit 3.7: Unit synthesis and lesson plan (90 min - 240+ min) This is the final part for the density unit and tasks students to apply their understanding of density concepts to create an NGSS lesson plan for an activity and apply problem-solving skills to a film-inspired thought experiment as a summative assignment for this unit.

Learning Outcomes:

Overall  Learning Outcomes:

  • Demonstrate How Scientists Observe the Unobservable: By investigating indirect evidence and utilizing theoretical models, students will repeatedly demonstrate the ability to infer the underlying properties and behavior of unseen structures.
  • Application of Density Principles to Complex Systems: Students will proficiently synthesize their understanding of density principles across various contexts, encompassing atmospheric, oceanic, and lithosphere-lithosphere layers, demonstrating the ability to explain and interpret layered structures across different materials.
  • Analyze Real-World Data: Students will proficiently analyze sea surface data, create ocean profiles, and generate hypotheses about upwelling and downwelling based on satellite imagery, demonstrating advanced data interpretation skills.
  • Synthesis of Density Principles and Conceptual Problem Solving: Students will synthesize NGSS principles with density concepts, showcasing their capacity to apply density-based problem-solving strategies to real-world scenarios and effectively communicate density concepts to diverse audiences.
  • Engagement with Density Concepts: Throughout the course, students will develop a deep appreciation for the significance of density principles and their implications for understanding natural phenomena, fostering a lasting curiosity and enthusiasm for exploring complex systems governed by density-driven processes.