Read a geological isotope clock
Infer a closed-system age and distinguish that age from sediment deposition.
Earth and space science
Reconstruct Earth history, test explanations and connect observations across time and scale.
This is the course outline. Open a unit to choose a lesson; every lesson opens on its own page. Explanations and experiments live inside those lesson pages.
Course scope and preparation
Teaching models make their assumptions explicit. Selected recorded evidence comes from earthquake, volcano, weather and climate sources; stellar source cards and a historical galaxy table identify their publications. Fictional specimens, prescribed interiors and calculated scenarios remain labeled separately from measurements. Public practice and completed notebooks do not establish independent mastery. The listed bounded teaching sequence and evidence workspaces are available; physical field competence requires separate observation and review.
Explore 116 lessons across Earth history, dynamic Earth, land and water, atmosphere and weather, climate, orbital geometry, and stellar and galaxy evidence. The 31 investigations connect predictions, diagrams and calculations with saved comparison captures and explanations.
Geological time and evidence
Diagnose a disturbed isotope clock
Quantify the effect of daughter loss and propose independent evidence to distinguish explanations.
Order rock layers and intrusions
Justify event order from specific contact evidence rather than height alone.
Read erosion surfaces and missing time
Use truncation and included fragments to place erosion in a history without inventing a time gap.
Keep unknown relationships in a geological history
Distinguish an unknown event order from simultaneity and combine relative order with conditional age bounds.
Minerals and Earth materials
Identify minerals from several properties
Use several independent properties to narrow a stated mineral candidate list.
Handle ambiguous and conflicting mineral evidence
Explain an empty candidate set and propose a targeted recheck without forcing an identification.
Classify rocks by their formation
Trace a supported formation process and identify observations needed to classify a rock.
Trace and repair rock-cycle pathways
Explain every transition in a selected route and preserve the last supported state when a step fails.
Separate metamorphism from melting
Distinguish metamorphic and igneous histories and explain why foliation is not required for metamorphism.
Plate motion and dynamic Earth
Measure plate motion in a shared frame
Calculate relative velocity component by component and distinguish speed from signed motion.
Interpret boundary motion and its limits
Classify local relative motion while withholding unsupported claims about subduction and hazards.
Project plate displacement with explicit assumptions
Calculate component displacements and explain what a constant-rate projection cannot establish.
Infer distance from seismic arrival times
Derive the distance rule from travel times and distinguish a supplied timing from an observed waveform pick.
Locate a compatible source from several stations
Use station geometry and residuals to distinguish one-station distance from a compatible planar location.
Separate rounding, grid resolution and model uncertainty
Explain a rounding band, a sampled grid match and omitted sources of location uncertainty.
Read and audit an earthquake catalog snapshot
Distinguish event time, catalog revision and retrieval time while preserving the identity and limits of a selected record.
Calculate moment ratios from logarithmic magnitude
Use magnitude differences and exponents correctly, including reciprocal and equal-record comparisons.
Separate magnitude, shaking intensity and damage
Reject unsupported site-shaking and damage comparisons while proposing suitable additional evidence.
Explain melting without a global molten layer
Explain decompression and volatile effects without treating the mantle as a liquid ocean.
Read what each deformation instrument measures
Calculate static station changes without confusing translation with extension.
Combine deformation with seismic evidence
Interpret approximate and bounded event-rate summaries with overlapping intervals.
Distinguish unrest, eruption and a revised report
Build a sourced timeline and keep gas emission rate distinct from concentration.
Defend a bounded geological interpretation
Write an evidence brief without a universal threshold or eruption-date claim.
Land, water and watersheds
Balance a watershed water budget
Construct a consistent water ledger and convert a basin-equivalent depth into volume.
Interpret declining storage and infeasible budgets
Explain output greater than precipitation and diagnose a negative ending-storage calculation without clamping it away.
Choose the boundary before counting water flows
Prevent double counting of recharge and baseflow and distinguish accounting closure from verified measurements.
Use hydraulic head to determine flow direction
Calculate the signed head gradient and explain why head is neither terrain height nor depth to water.
Calculate Darcy flux and volumetric flow
Calculate signed Darcy flux and discharge with consistent units and interpret controlled conductivity comparisons.
Estimate ideal groundwater transit and its limits
Calculate a conditional advective crossing time without presenting it as a contaminant-arrival forecast.
Calculate suspended-sediment transport through time
Convert concentration and discharge to a mass rate and distinguish concentration, rate and accumulated load.
Test how sampling timing changes a sediment estimate
Explain why concentration timing matters and why one coincidentally correct estimate does not validate a sampling method.
Separate suspended load from catchment erosion
State what a gauge load measures and identify additional evidence needed for erosion or intervention claims.
Distinguish weathering from movement
Justify a process interpretation from supplied observations rather than appearance alone.
Compare exposed area after fragmentation
Calculate piece count and surface-area ratios without claiming a weathering-rate law.
Compare rainfall timing with water entry
Calculate hourly rain partition while preserving event water balance.
Track initial water and remaining capacity
Compare wet and dry initial conditions without changing the storm.
Bound a runoff interpretation
Defend a model comparison and identify observations needed for a field inference.
Atmosphere and oceans
Connect air pressure to the mass above
Convert pressure units and calculate hydrostatic column mass per area with explicit assumptions.
Explore pressure decrease and atmospheric scale height
Interpret scale height and calculate a pressure-level altitude in an isothermal column.
Compare atmospheric models without overclaiming
Distinguish fixed-pressure from fixed-altitude comparisons and identify observations needed to test an atmospheric model.
Explain relative humidity without adding water
Calculate relative humidity and explain why it can change while the modeled vapor mixing ratio remains fixed.
Find dew point as an inverse saturation calculation
Calculate dew point and interpret its relation to air temperature under the stated liquid-water assumptions.
Interpret saturation limits without hiding the result
Diagnose RH above 100% and state what extra processes and observations are needed to predict condensation.
Compare a lifted parcel with its environment
Calculate parcel and environmental temperatures at a shared height and distinguish a prescribed lift from a predicted trajectory.
Estimate a lifting condensation level
Derive the approximate LCL and retain continuity across the change in cooling rate.
Interpret a temperature-only stability comparison
Explain a temperature-contrast sign change and identify missing physics needed for actual convection diagnostics.
Audit recorded weather observations
Separate observation time from retrieval time and reproduce a unit conversion without inventing metadata.
Compare reported and calculated weather humidity
Calculate RH from the two saturation pressures and interpret agreement without assuming independent measurements.
Limit weather claims to the recorded evidence
Reject unsupported zero-rainfall, pressure-gradient and climate conclusions and specify additional evidence needed.
Why does air move?
Explain force versus velocity while distinguishing spatial pressure gradients from temporal change.
Unequal heating and circulation patterns
Interpret circulation cells as imperfect climatological patterns rather than fixed parcel trajectories.
Audit a recorded time series
Preserve UTC, field scales and meteorological wind conventions in endpoint comparisons.
Assemble a multi-variable front argument
Make a timed, bounded interpretation and distinguish cold-front and warm-front geometry.
Defend limits and transfer
Retain supported observations while identifying missing discriminating evidence.
Connect winds, boundaries and surface currents
Explain why a wind arrow alone does not determine an ocean current.
Compare temperature and salinity contributions
Calculate both signed contributions without treating the rule as a validated seawater equation.
Interpret a two-layer density comparison
Explain stable, unstable and neutral layering under the common-pressure teaching assumptions.
Read a recorded ocean profile
Report a reproducible profile difference with provenance, units and unavailable metadata.
Follow water and energy without a conveyor shortcut
Distinguish a density tendency from measured velocity, volume transport and heat transport.
Earth in space
Explain opposite seasons with axial tilt
Explain how axial orientation changes seasonal illumination without requiring a change in the Sun’s output.
Project sunlight onto a horizontal area
Calculate a geometric projection and explain why a lower Sun spreads the same beam over a larger horizontal area.
Combine daylight duration and solar angle
Distinguish noon conditions from a full-day integral and interpret the model’s geometric daylight convention.
Distinguish seasonal geometry from changing solar output
Explain model predictions while separating them from measured validation, temperature response and exact calendar forecasts.
Separate lunar illumination from the visible disk
Calculate apparent illuminated fraction while distinguishing it from the fraction of the physical lunar surface lit by the Sun.
Read lunar phases as changing viewing geometry
Relate elongation to apparent illumination and explain why a single fraction does not identify the phase branch.
Connect orbital nodes to three-dimensional alignment
Use latitude, elongation and centerline offset to explain why a node or near-full phase alone is insufficient for alignment.
Evaluate eclipse claims against model evidence
Write a bounded evidence claim and identify missing information needed for actual eclipse occurrence and local visibility.
Explain gravity and acceleration in orbit
Explain tangent velocity and inward acceleration, and calculate how gravitational acceleration changes with radius.
Connect circular speed, period and position
Relate circumference, speed and elapsed time to the selected orbit’s displayed position.
Predict orbital changes with radius ratios
Calculate speed, period and gravity ratios for the same central body and explain the circular form of Kepler scaling.
Evaluate circular-orbit evidence and limits
Write a bounded model conclusion and specify independent observations needed to evaluate a circular approximation.
Climate and planetary energy
Account for planetary incoming and outgoing energy
Calculate incoming, reflected, absorbed and outgoing terms without double-counting reflection or confusing flux with temperature.
Solve for an effective radiative equilibrium
Calculate equilibrium effective emitting temperature and distinguish it from mean surface temperature and a timed adjustment.
Compare prescribed planetary albedos
Calculate an albedo perturbation and explain why manually selected albedos do not simulate a temperature response.
Bound climate claims with energy evidence
Write an evidence-based scope statement and design compatible radiative and energy-storage comparisons.
Build a one-layer greenhouse energy balance
Solve the surface and layer equilibrium equations while handling zero emissivity without inventing a temperature.
Audit surface, atmosphere and space fluxes
Check all radiative balances without double-counting absorbed surface radiation.
Compare greenhouse parameter sensitivities
Calculate emission and temperature ratios while separating parameter sensitivity from real climate sensitivity.
Evaluate greenhouse evidence and model limits
Write a bounded mechanism claim and identify missing spectral, dynamical and observational evidence.
Interpret temperature anomalies and reference periods
Calculate a reference shift and distinguish anomalies, absolute temperatures, rounding and observational uncertainty.
Compare climate windows and trend summaries
Calculate a per-decade endpoint change and explain how all-year fits and interval choices affect descriptive summaries.
Compare climate indicators with their metadata
Build a paired evidence ledger without replacing missing observations or treating concentration as emissions.
Separate climate observations from attribution claims
Audit a climate comparison and specify additional evidence needed for attribution and uncertainty assessment.
Connect energy imbalance to temperature change
Calculate initial warming and stored-energy anomalies for a synthetic effective reservoir.
Separate response time from equilibrium
Use capacity and net damping to calculate response time and explain incomplete approach to equilibrium.
Trace a temperature-dependent feedback loop
Calculate baseline and feedback contributions and explain the positive net-damping condition.
Follow stored energy after forcing removal
Calculate before-and-after removal balances and distinguish a positive anomaly from ongoing warming.
Diagnose response curves with independent clues
Justify a parameter diagnosis using initial rate, target and response time rather than a single curve point.
Compare observed warming with forcing counterfactuals
Calculate descriptive residuals and interpret long-term comparisons without treating ensemble bands as a standalone attribution test.
Interpret assessed human and natural contributions
Explain the assessed attribution conclusion without double-counting totals or treating central zero as absence.
Match attribution intervals to their meaning
Audit uncertainty and scope without inventing joint distributions from marginal endpoints.
Write a supported historical attribution claim
Produce a reproducible brief that states the supported human-influence conclusion and identifies limits on extrapolation.
Stars and cosmic evidence
Read what spectral features represent
Interpret supplied feature positions and explain what a schematic spectrum cannot establish.
Identify a pattern with multiple lines
Calculate residuals and use multiple features without inventing certainty or treating unreported lines as nondetections.
Correct an instrument offset with separate evidence
Calculate a shared additive correction and reject a one-offset calibration when standards disagree.
Preserve ambiguity and diagnose conflicting evidence
Write a bounded spectral claim and propose a discriminating next observation without claiming a verified mixture or abundance.
Use continuum shape as a conditional thermometer
Calculate a peak temperature under explicit wavelength and coverage assumptions.
Connect surface emission to total stellar power
Calculate luminosity ratios and keep W, W/m² and per-wavelength quantities separate.
Separate emitted power from received flux
Calculate received-flux ratios and identify assumptions needed to infer distance from brightness.
Identify what stellar evidence cannot determine
Explain radius-distance degeneracy and distinguish total brightness from continuum shape.
Track hydrogen through the pp-I chain
Recover net fuel consumption and explain the electron inventory.
Calculate the small rest-mass difference
Calculate total released energy with a consistent electron inventory.
Separate deposited energy from neutrino escape
Calculate a conditional completion rate from deposited energy and photon demand.
Compare fuel inventory with average power
Calculate accessible hydrogen and explain why energy divided by power is not a measured lifetime.
Read stellar positions and pathways
Distinguish an H-R position from a unique evolutionary stage.
Follow core and shell changes
Explain how shell burning can continue after central hydrogen exhaustion.
Separate age from evolutionary order
Distinguish chronological age, stage order and a conditional energy-budget duration.
Compare possible stellar outcomes
Explain why hot objects can have different histories and why outcomes need more than initial mass.
Connect synthesis with released material
Bound an element-production claim using the actual scope of spectral evidence.
Defend an evolutionary interpretation
Separate a conditional pathway from a unique inverse inference.
Identify a galaxy from complementary evidence
Distinguish appearance from unique distance or age.
Recover a fractional shift after calibration
Calculate consistent fractional shifts and distinguish them from additive instrument error.
Compare redshift with independent distance
Describe an overall relation while retaining scatter, negative velocities and historical limits.
Separate common calibration from scatter
Predict inverse slope scaling and distinguish feasibility from probability.
Build an evidence-limited cosmic argument
Defend a bounded expansion argument without circular distance evidence or unsupported age claims.
Projects, practice and evidence
The cumulative evidence brief and fourteen public assessment cases are available below. Independent review and course-wide delivery evaluation remain separate requirements. Further field investigations and advanced models will support later study, including college geology. This sequence does not establish completion of that separate offering.
Scientific inquiry and chemistry provide optional refreshers. Every lesson is directly accessible.
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