Measure cells without confusing size and magnification
Calibrate synthetic and recorded images, document endpoint choices and distinguish measurement from interpretation.
Biology and living systems
Explain living systems by connecting measurements, matter, energy and inherited information.
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
The first twenty-eight lessons are available: cell measurement, cellular organization, diffusion, osmosis, enzyme investigations, photosynthesis, respiration, carbon accounting, coding sequences, meiosis, inheritance, evolution, organism regulation and ecology. A seed-growth notebook now supports your own repeated observations and a saved report. Twenty-two public cases, in the original and expanded sets, support answer practice and saved explanation drafts. Two measured-data lessons use the frozen CC0 Palmer penguins dataset to investigate variation, missingness and confounding. The cell-measurement lesson also provides a licensed onion micrograph with calibration, uncertainty and records you can append to your reflection. This bounded teaching sequence includes retained investigation and assessment workflows. Broader study and authentic practical evaluation remain distinct from authored content.
Use arithmetic, ratios and graph reading. Each investigation explains its additional mathematics. No programming is required. Scientific inquiry supplies optional preparation in fair comparisons and evidence.
0/28 currently published notebooks completed. Your saved lesson records are retained independently of course-content updates. This count is not full-course completion or demonstrated mastery.
Continue: Measure cells without confusing size and magnificationCells, scale and organization
Connect cell structures to the work they do
Explain how membranes, ribosomes and genetic material support cellular functions without inferring invisible structures from size alone.
Membranes and transport
Explain diffusion through opposing flows
Distinguish net movement from the continuing motion of particles at equilibrium.
Track water while solute stays behind
Use water and solute conservation to explain osmotic redistribution and recognize the effect of pressure in real cells.
Enzymes and controlled rate investigations
Find the limiting factor in an enzyme reaction
Explain saturation and distinguish a rate from the total amount of product.
Design evidence that separates enzyme explanations
Design a substrate series with controls and distinguish capacity evidence from claims about temperature or pH.
Photosynthesis, respiration and carbon
Explain how light supports carbon fixation
Connect light capture, carbon fixation and an observable gas signal without treating light as matter.
Account for atoms in aerobic respiration
Balance an ideal glucose-oxygen reaction and distinguish its material endpoint from rate and ATP yield.
Interpret a zero gas signal
Use a light-dark comparison to separate competing interpretations and state its assumptions.
Track carbon through fixation and respiration
Construct a conserved carbon ledger and distinguish organic-carbon change from wet mass or energy.
Information, division and inheritance
Connect a coding sequence to a translation outcome
Distinguish coding-strand DNA, an mRNA codon and an amino-acid assignment while stating the fixed-frame assumption.
Separate a sequence change from a trait claim
Classify the modeled coding consequence without inferring an organism-level effect from a codon alone.
Count chromosome sets separately from DNA copies
Explain why DNA replication does not double ploidy and why meiosis reduces chromosome sets.
Build an inheritance prediction from gametes
Calculate genotype probabilities and distinguish genotype, phenotype and allele frequency.
Compare offspring counts with an inheritance model
Interpret sampling variation without selectively reporting seeds that match a preferred ratio.
Evolution and diversity
Explain selection without giving evolution a goal
Calculate a normalized next-generation frequency and identify conditions that the model excludes.
Distinguish drift from a selective advantage
Explain how allele frequencies can change under neutral sampling and compare replicated simulations without cherry-picking.
Compare tree hypotheses with character evidence
Interpret an unrooted quartet and compare minimum-change explanations without treating the best score as proof.
Separate allele divergence from species formation
Explain symmetric gene flow and distinguish geographic separation, genetic difference and reproductive isolation.
Organisms and regulation
Trace a negative-feedback response
Explain negative feedback as an interacting process and distinguish a model target from a biological normal range.
Connect roots, leaves and a water budget
Reconcile plant water fluxes and explain how stomatal responses connect water balance with gas exchange.
Populations, communities and ecosystems
Challenge an unlimited-growth prediction
Interpret carrying capacity as a contextual model parameter and identify when a coarse update gives an implausible forecast.
Keep food-web energy and nutrient accounts separate
Calculate successive energy transfers without treating efficiency as universal or energy as a cycling nutrient.
Measure abundance without overlooking diversity
Distinguish abundance density from detected richness and explain how spatial selection changes ecological evidence.
Investigate measured variation in penguins
Reconstruct a measured-data summary and distinguish biological variation, missingness and measurement uncertainty.
Compare observational groups without inventing causation
Identify confounding in observational comparisons and design a better-supported follow-up.
Track nitrogen through an ecosystem
Reconstruct a simultaneous nutrient update and explain how changing one transfer affects several pools.
Distinguish recycling from ecological recovery
Track a disturbance across a system boundary and specify which recovery outcomes the model cannot establish.
Projects, practice and evidence
Cumulative investigation
Plan and analyze a seed-growth studyKeep plant identities, missing observations and comparison groups explicit. A saved submission requires human review.
Separate transfer cases
Practice biology transfer casesThe cases include reinforcement as well as transfer practice. First responses and feedback exposure are retained. Public case results do not establish course mastery.
What counts as evidence?
Twenty-two CPU teaching models produce synthetic predictions; the separate penguin workbench analyzes recorded measurements. Captures preserve the appropriate model settings or frozen-dataset filters and explanations, not physical laboratory competence. The recorded onion image supports image measurement; practical microscope operation still needs observation and review beyond this release. Practice feedback checks particular claims; it does not automatically grade an entire scientific argument.
Save a science backup or import one
Science work is stored locally in this browser, separately from mathematics and AI. It does not sync automatically. Use this science-only backup; this checkout's older all-subject export does not include science.
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Matching imported notebook drafts replace their current drafts. Omitted lessons and known first attempts remain. Export your current work first if you want to retain both drafts.
Complete file sets and course backups
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