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High School Earth and Space Science: Talk Through the Whole System
This course covers NGSS high school Earth and Space Sciences from the origin of the universe to the engineering trade-offs humans face managing Earth's resources. You'll work through gravity and orbits, how stars make the elements, Earth's layered interior and plate tectonics, the rock cycle, water's odd properties, the carbon cycle, the coevolution of life and atmosphere, and finish with hazard planning, energy policy trade-offs, and climate forecasting using real data and simple models.
Instead of reading a chapter and answering review questions, you talk with a tutor that asks you to reason it out. If you say seafloor spreading happens because plates 'just move apart,' the tutor asks what's pushing them, and walks you toward thermal convection in the mantle. It tracks separately whether you can explain an idea, like why massive stars die faster, and whether you can actually do the related work, like reading a Hertzsprung-Russell diagram or calculating an isotope's remaining fraction after three half-lives.
Who it is for
- High schoolers taking an Earth or space science course, with NGSS or a similar standard
- Students who've had middle school physical and life science and basic algebra, including proportional reasoning and linear equations
- Parents choosing a self-paced science option that covers astronomy, geology, and climate together
- Teachers wanting a resource that pairs concept explanations with calculation practice, like half-life problems or Kepler's third law
- Students preparing for an Earth science Regents exam or similar end-of-course test
What you will be able to do
- Explain how gravity produces orbits and apply Kepler's laws to planets and satellites
- Trace a star's life cycle and explain how fusion builds elements up through iron, with supernovae making the rest
- Use seismic wave data and radiometric dating to describe Earth's interior and history
- Explain plate tectonics as driven by mantle convection, with supporting evidence like seafloor magnetic striping
- Trace carbon and water through Earth's four systems and explain feedback loops in climate
- Evaluate energy and resource trade-offs and justify a design choice using weighted criteria and simulation data
A taste of a lesson on Thermal Convection and the Cycling of Matter in Earth's Interior
The tutor asks, you answer, and it works from what you actually said. No videos to sit through.
The 29 topics in Earth and Space Science
Each topic builds on the ones before it. The tutor checks what you already know and starts there.
Gravity and Orbital Motion
Newton's law of universal gravitation (F = Gm1m2/r^2) and how it produces orbits. Students use Kepler's three laws (elliptical orbits, equal areas in equal times, T^2 proportional to a^3) and apply them with mathematical or computational models to predict the period and motion of planets, moons, and satellites in the solar system. Real understanding means predicting orbital periods from orbit size and explaining why orbital speed changes along an ellipse.
Structure and Origin of the Solar System
Inventory of the solar system: the Sun, terrestrial and giant planets, moons, asteroids, comets, and Kuiper belt objects, and their compositions and locations. Key ideas are the nebular hypothesis (a collapsing rotating cloud flattening into a disk), the separation of rocky and gas/ice bodies by temperature, and the evidence supporting these ideas. Real understanding means connecting observed patterns (orbits in one plane, planets in one direction of spin) to the formation model.
Builds on Gravity and Orbital Motion
Light, Spectra, and the Doppler Effect
Electromagnetic radiation as a wave with wavelength and frequency; the electromagnetic spectrum; blackbody radiation and how surface temperature sets peak wavelength; atomic emission and absorption spectra as fingerprints of elements; and the Doppler shift, where motion toward or away from an observer shifts wavelength (redshift and blueshift). Real understanding means reading a spectrum to infer composition, temperature, and motion.
Nuclear Fusion and Energy in Stars
Nuclear binding energy and mass-energy equivalence (E = mc^2) explained at a conceptual level; how fusion of hydrogen into helium in the Sun's core releases energy, with the mass defect; why the core needs extreme temperature and pressure to overcome electrostatic repulsion; how this energy travels outward by radiation and convection and reaches Earth as electromagnetic radiation. Real understanding includes the reason the Sun's core, not its surface, is the energy source.
Builds on Light, Spectra, and the Doppler Effect
Life Cycle of Stars and Model Building
Stars form from collapsing gas clouds, reach hydrostatic equilibrium between gravity and pressure, and their life span depends on mass (more massive stars burn fuel faster and live shorter lives). Students build an evidence-based model of the Sun's life span (about 10 billion years on the main sequence, with its fuel supply in the core) and trace its future as a red giant and white dwarf, and in massive stars, supernovae and neutron stars or black holes. Real understanding means explaining why mass controls lifetime and using an HR diagram to place stars.
Builds on Gravity and Orbital Motion, Structure and Origin of the Solar System, Nuclear Fusion and Energy in Stars
How Stars Produce the Elements
Stellar nucleosynthesis: fusion in stars builds elements up to iron, with lighter stars making helium and carbon and massive stars building heavier elements through successive fusion stages. Supernovae and neutron star mergers create heavier elements beyond iron. Students communicate the sequence clearly, explaining why iron is an endpoint for energy-releasing fusion and where elements heavier than iron come from. Real understanding means explaining in plain language how the atoms in the human body were made in stars.
Builds on Life Cycle of Stars and Model Building
Galaxies, the Milky Way, and the Scale of the Universe
The scale of the universe: light-year and parsec distances, the Sun's location in the Milky Way's disk and spiral arms, the structure of galaxies (spiral, elliptical, irregular), galaxy clusters, and the large-scale cosmic web. Students learn how distances are estimated (parallax for nearby stars, standard candles such as Cepheid variables and Type Ia supernovae) and how galaxies are grouped. Real understanding means explaining how astronomers measure distance and why the universe is organized into galaxies and clusters.
Builds on Light, Spectra, and the Doppler Effect, Life Cycle of Stars and Model Building
The Big Bang and Evidence for an Expanding Universe
Hubble's discovery that distant galaxies recede with speed proportional to distance (Hubble's law), the redshift of galaxy spectra as evidence of expansion, the cosmic microwave background as relic radiation from the early hot universe, and the observed abundances of hydrogen and helium (about 75% and 25% by mass) consistent with Big Bang nucleosynthesis. Students construct an explanation linking these three lines of evidence to the Big Bang theory. Real understanding means explaining why the expansion implies a hotter, denser past, and why the evidence is independent.
Builds on Light, Spectra, and the Doppler Effect, Life Cycle of Stars and Model Building, Galaxies, the Milky Way, and the Scale of the Universe
Radioactive Decay and Radiometric Dating
Radioactive isotopes decay at a constant rate characterized by half-life; the parent-to-daughter ratio gives an age; examples include uranium-lead, potassium-argon, and carbon-14 (useful only for recent organic material). Students calculate ages from fractions of parent remaining using half-life, and explain why dating works only for materials that were closed systems at formation and why igneous rocks are dated rather than sediments. Real understanding means reasoning from exponential decay to an age and judging whether a date is reliable.
Earth's Formation and Early History
Earth formed about 4.6 billion years ago by accretion of planetesimals in the solar nebula, with heating from impacts and radioactive decay producing a molten early Earth and differentiation into core, mantle, and crust. Evidence includes radiometric dating of meteorites (about 4.56 billion years), the oldest zircon crystals (about 4.4 billion years), lunar and Martian surfaces, and the cratering record. Students apply reasoning from ancient Earth materials, meteorites, and planetary surfaces to build an account of early Earth, including the early atmosphere and oceans. Real understanding means using radiometric dating and crater counts as evidence about time.
Builds on Structure and Origin of the Solar System, Radioactive Decay and Radiometric Dating
Earth's Interior Structure and Seismic Evidence
Layers of Earth defined by composition (crust, mantle, core) and by mechanical properties (lithosphere, asthenosphere, mesosphere, inner and outer core). Seismic waves: P-waves and S-waves, how S-waves cannot pass through liquid and how P-wave speed changes reveal the liquid outer core, and shadow zones. Students use seismic evidence to model layers. Real understanding means explaining what evidence supports each boundary and why the layers differ.
Builds on Gravity and Orbital Motion
Plate Tectonics and the Ages of Crustal Rocks
Continental drift and the theory of plate tectonics: lithospheric plates move over the asthenosphere; evidence includes matching fossils and rock formations across continents, seafloor magnetic striping from reversals, seafloor spreading, and ocean-floor age increasing away from mid-ocean ridges. Students evaluate evidence of past and present plate movement (GPS, earthquake and volcano distributions) and use it to explain why oceanic crust is young (under about 200 million years) while continental crust can be over 4 billion years old. Real understanding means using rock and seafloor evidence to argue for moving plates.
Builds on Earth's Interior Structure and Seismic Evidence
Thermal Convection and the Cycling of Matter in Earth's Interior
Heat flows from the hot core and radioactive decay in the mantle, creating thermal convection: hot, less dense material rises, cools, and sinks, slowly cycling matter. Students develop a model based on evidence of Earth's interior (heat flow, seismic tomography, density differences) that describes this cycle and connects it to mantle plumes, ridge push, and slab pull as drivers of plate motion. Real understanding means explaining how density and temperature drive a convection cell and how the cell links to surface plate motion.
Builds on Earth's Interior Structure and Seismic Evidence, Plate Tectonics and the Ages of Crustal Rocks
Rock Cycle and Earth's Surface Processes
The rock cycle: igneous, sedimentary, and metamorphic rocks and how each transforms through melting, weathering, erosion, deposition, lithification, heat, and pressure. Surface processes (weathering, erosion, deposition) are driven by water, wind, ice, and gravity. Students describe how plate-scale processes (uplift, subduction, volcanism) and surface processes (erosion) together form continental and ocean-floor features across time and space scales, such as mountain ranges, rift valleys, trenches, and abyssal plains. Real understanding means relating a landform to both an internal driver and a surface process and to the time scale on which each acts.
Builds on Thermal Convection and the Cycling of Matter in Earth's Interior
Relative Dating and the Geologic Time Scale
Relative dating principles: superposition, original horizontality, cross-cutting relationships, and inclusions, used to order rock layers and events without numerical ages. Students combine relative ordering with radiometric anchor dates to read a geologic column and build the geologic time scale (eons, eras, periods) and the major events it records, including mass extinctions and the appearance of major life forms. Real understanding means ordering a sequence of geologic events from cross-cutting and superposition evidence and explaining how radiometric dates calibrate the scale.
Builds on Radioactive Decay and Radiometric Dating, Rock Cycle and Earth's Surface Processes
Properties of Water and Its Effects on Earth Materials
Water's unusual properties: polarity and hydrogen bonding, high specific heat, density maximum at 4 degrees C (ice floats), high heat of vaporization, and its role as a solvent. Effects on Earth materials and surface processes include freeze-thaw weathering, chemical weathering by dissolution and acid rain, sediment transport by flowing water, and groundwater flow through permeable rock. Students plan and conduct a simple investigation (for example, testing how water's properties change weathering or erosion rates) and interpret the data. Real understanding means designing a fair test and explaining the water property behind each observed effect.
Builds on Rock Cycle and Earth's Surface Processes
Earth's Systems and Feedback Loops
Earth as four interacting systems: geosphere, hydrosphere, atmosphere, and biosphere, with matter and energy exchanged among them. Positive and negative feedback loops. Students analyze geoscience data to argue that a single change to one part of the surface (for example, deforestation, glacier retreat, or volcanic eruption) produces feedbacks that alter other systems, such as albedo-driven warming from ice loss or CO2 release from thawing permafrost. Real understanding means tracing the chain of cause and effect across at least two systems and identifying whether each link amplifies or damps the change.
Builds on Properties of Water and Its Effects on Earth Materials
Energy Balance and Climate Variations
Earth's energy budget: incoming solar radiation, albedo, outgoing longwave radiation, and the greenhouse effect. Variations in energy flowing into and out of the systems (Milankovitch cycles of orbital eccentricity, axial tilt, and precession; changes in solar output; volcanic aerosols; albedo changes) cause climate change over time. Students use a model (energy budget diagram or simple radiative balance) to describe how each variation changes climate. Real understanding means predicting the direction of temperature change from a change in energy input or output.
Builds on Light, Spectra, and the Doppler Effect, Earth's Systems and Feedback Loops
The Carbon Cycle
Carbon moves among reservoirs: atmosphere (CO2), hydrosphere (dissolved carbon and ocean carbonate), geosphere (carbonate rock, fossil fuels, and volcanic outgassing), and biosphere (photosynthesis and respiration). Students develop a quantitative model using reservoir sizes and flux rates (in petagrams of carbon per year) and calculate residence times and the effect of a flux imbalance on atmospheric CO2. Real understanding means reading a box-and-arrow carbon budget and computing how long a change in one flux takes to change a reservoir.
Builds on Properties of Water and Its Effects on Earth Materials, Earth's Systems and Feedback Loops
Coevolution of Earth's Systems and Life
Life and Earth's systems have evolved together: photosynthetic cyanobacteria produced the Great Oxidation Event and oxygen-rich atmosphere (about 2.4 billion years ago); the ozone layer formed from atmospheric oxygen; biological weathering and carbon burial by organisms altered atmospheric CO2; banded iron formations and stromatolites record early life. Students construct an argument with evidence that Earth's systems and life changed simultaneously rather than one causing the other alone. Real understanding means citing at least two lines of evidence and explaining the feedback between biology and geochemistry.
Builds on Earth's Formation and Early History, Relative Dating and the Geologic Time Scale, The Carbon Cycle
Natural Resources, Hazards, and Human History
Natural resources (water, fertile soil, minerals, fossil fuels, and wind or solar energy) and natural hazards (earthquakes, volcanoes, floods, droughts, hurricanes) have shaped where and how people settled and farmed; climate changes such as the Little Ice Age or droughts have triggered migrations and collapses. Students construct an explanation from evidence of how these factors influenced human activity across historical and regional examples. Real understanding means linking a specific resource or hazard to a specific pattern of settlement or history with evidence.
Builds on Rock Cycle and Earth's Surface Processes, Energy Balance and Climate Variations
Engineering Design: Criteria, Constraints, and Trade-offs
The engineering design process applied to Earth problems: analyzing a major global challenge to specify qualitative and quantitative criteria and constraints that account for societal needs and wants; breaking a complex problem into smaller solvable sub-problems; and evaluating solutions against prioritized criteria (cost, safety, reliability, aesthetics, social, cultural, and environmental impact). Real understanding means writing measurable criteria and constraints and using a weighted decision matrix to choose between designs.
Builds on Natural Resources, Hazards, and Human History
Cost-Benefit Evaluation of Energy and Mineral Resources
Competing design solutions for developing, managing, and using energy (fossil fuels, nuclear, wind, solar, hydro, geothermal) and mineral resources (mining, recycling, substitution). Students compare cost-benefit ratios including energy return, environmental impacts, land use, and cost of extraction and disposal, and evaluate which solution is best under stated criteria. Real understanding means computing or estimating cost-benefit ratios and defending a choice with explicit trade-offs.
Builds on Engineering Design: Criteria, Constraints, and Trade-offs
Sustainability, Populations, and Biodiversity Simulation
Human population growth, carrying capacity, and resource management, and how harvest rates affect fish stocks, forests, and biodiversity. Students create a computational simulation (for example, a logistic growth model with a harvesting term) that shows the relationships among resource management, population sustainability, and species diversity, and interpret how changing a parameter changes outcomes. Real understanding means identifying the harvest rate threshold for sustainability and explaining why biodiversity loss reduces system resilience.
Builds on Natural Resources, Hazards, and Human History
Human Impacts on Natural Systems and Technological Remediation
Human activity alters natural systems: air and water pollution, land use change, ocean acidification, and habitat loss. Students evaluate or refine a technological solution that reduces these impacts (for example, scrubbers, wastewater treatment, carbon capture, or fish ladders), using measurable criteria and trade-offs. Real understanding means identifying the specific impact a technology targets, the measure of success, and the side effects that must be weighed.
Builds on The Carbon Cycle, Sustainability, Populations, and Biodiversity Simulation
Evidence-Based Forecasting of Climate Change
Analyzing geoscience data (global temperature records, CO2 Keeling curve, sea-level records, ice-core data) and outputs of global climate models to make an evidence-based forecast of the current rate of global or regional climate change and its future impacts (sea-level rise, ocean acidification, heat waves, changes in precipitation and ecosystems). Students evaluate model uncertainty and the agreement between models and observations. Real understanding means reading a time series to compute a rate of change and justifying a forecast with data.
Builds on Energy Balance and Climate Variations, The Carbon Cycle
Interpreting Coupled Models of Human-Modified Earth Systems
Interpreting a provided simple coupled model (for example, a box model linking CO2, temperature, and sea level) and running one scenario, such as a fossil fuel emissions change or a land use change, to show how a human-driven change propagates through the atmosphere, hydrosphere, geosphere, and biosphere. Students identify each linkage the scenario reveals and check whether the model's output matches the observed data. Real understanding means running a single scenario and explaining each linkage it reveals.
Builds on Coevolution of Earth's Systems and Life, Evidence-Based Forecasting of Climate Change
Testing Design Variables in Earth-System Simulations
Using a provided computer simulation of a complex real-world problem (for example, a flood defense, a coastal management plan, or an energy portfolio) to test how changing one design variable shifts outcomes across several criteria, including interactions within and between systems. Students identify which interactions in the simulation matter most for the outcome. Real understanding means predicting and checking how one design change propagates through the simulated system.
Builds on Cost-Benefit Evaluation of Energy and Mineral Resources, Human Impacts on Natural Systems and Technological Remediation, Interpreting Coupled Models of Human-Modified Earth Systems
Weighting Criteria and Choosing Among Simulated Solutions
Using the outputs of simulated scenarios to score competing solutions against several criteria, applying different priority weights, and determining how the 'best' solution changes with those weights. Students build a weighted decision matrix, test sensitivity to the weights, and defend a recommendation with explicit trade-offs among cost, safety, reliability, aesthetics, and social and environmental impact. Real understanding means showing that a 'best' solution depends on the weights given to criteria and justifying the chosen weights.
Builds on Testing Design Variables in Earth-System Simulations
Practice questions in Earth and Space Science
A few of the kinds of questions you will work through, with answers.
A planet orbits the Sun at 4 times the distance Earth does. Using Kepler's third law (T² proportional to a³), roughly how many Earth years is its orbital period?
See the answer
About 8 years
T² = a³, so T² = 4³ = 64, and T = √64 = 8.
A rock sample has 1/8 of its original parent isotope remaining. If the half-life is 1.3 billion years, how old is the rock?
See the answer
About 3.9 billion years
1/8 means three half-lives have passed (1/2 → 1/4 → 1/8), and 3 × 1.3 billion = 3.9 billion years.
Why are rocks on the ocean floor generally much younger than rocks on the continents?
See the answer
Oceanic crust is continuously created at mid-ocean ridges and recycled into the mantle at subduction zones
Seafloor spreading constantly replaces oceanic crust, while continental crust is not subducted and can persist for billions of years.
Why does ice float on liquid water instead of sinking?
See the answer
Ice is less dense than liquid water
Hydrogen bonds arrange water molecules into an open hexagonal lattice when frozen, giving ice a lower density than liquid water near 4°C.
If fossil fuel burning adds carbon to the atmosphere faster than oceans and plants can absorb it, what happens to the atmospheric CO2 reservoir?
See the answer
It increases
A reservoir grows when the input flux exceeds the output flux, and current carbon uptake by oceans and biosphere doesn't match emission rates.
A town compares wind power and natural gas for a new power plant using criteria of cost, reliability, and carbon emissions. Why might the 'best' choice differ depending on how the town weights those three criteria?
See the answer
Each option scores differently on each criterion, so the overall ranking depends on which criteria are prioritized
Wind may score better on emissions but worse on reliability without storage, while gas may score better on reliability but worse on emissions, so changing the weight on each criterion can flip which option wins.
Questions about this subject
Does this course require calculus or advanced physics?
No. It uses the algebra skills from middle school, like solving linear equations and working with ratios and proportions, applied to formulas such as Kepler's third law and half-life decay.
How much of this is astronomy versus geology versus climate?
Roughly the first third covers stars, the solar system, and the universe, the middle third covers Earth's interior, rock cycle, and water, and the final third covers carbon, climate, and human resource and design decisions.
Are the simulations and models real software I need to install?
No, the simulations described, like box models of CO2 and sea level or population harvest models, are worked through conceptually and with provided data sets in the lesson, not through separate downloaded software.
Does this course cover detailed atmospheric chemistry or weather forecasting?
No, the course stops before detailed atmospheric chemistry; weather systems and climate are covered only at the level of energy balance, feedback loops, and long-term trends needed for HS-ESS2 and HS-ESS3.
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