About

The standard

Content here is authored against the Learning Content Architecture Standard 1.0. The knowledge graph is authoritative: lessons, practice, review, and reference are projections over the same underlying objects rather than separate documents.

Every objective states an observable performance, names the evidence that would support it, and is linked to the instruction that teaches it and the practice that exercises it. An objective with no evidence rule, or with no instructional coverage, cannot be published: the validator refuses the build.

What counts as evidence

Progress is inferred from evidence, not from pages visited. Every recorded response carries three separate facts: who scored it, how far that scoring can be trusted, and what it is allowed to establish. They are kept apart because they genuinely differ — a reviewed answer key and a learner's own judgment of their prose are both “scored”, and only one of them is an observation of the performance.

Self-assessment is recorded and shown, and it never advances a competence state on its own. An objective counts as independently performed only when the system holds scoring its evidence rule admits for that claim. Where it does not, the objective stays at the state the evidence supports and the reason is stated rather than hidden.

Mathematics and accessibility

Mathematics is stored as LaTeX and rendered to MathML, so assistive technology receives an expression tree rather than a picture. The site targets WCAG 2.2 Level AA across complete learner paths, and the accessibility rules that can be checked automatically run on every build.

Authoring provenance

Material drafted with AI assistance carries that provenance until a human reviewer has checked it.

Sources

Pedagogical rules implemented in this system are registered with an authority class distinguishing external technical standards, professional guidelines, empirical research, and house policy. House policy is labeled as such rather than presented as scientific consensus.

• A Brief Introduction to Evidence-Centered Design (2003) — empirical study
• A cornerstone of adaptivity - A meta-analysis of the expertise reversal effect (2025) — empirical study
• A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012) — consensus report
• A Meta-analysis of the Worked Examples Effect on Mathematics Performance (2023) — empirical study
• All of Statistics: A Concise Course in Statistical Inference (2004) — canonical textbook
• An Introduction to Statistical Learning with Applications in R (2021) — canonical textbook
• Calculus: Early Transcendentals (2020) — canonical textbook
• Category Theory (2010) — canonical textbook
• Category Theory for Programmers (2019) — canonical textbook
• Causal Inference for Statistics, Social, and Biomedical Sciences: An Introduction (2015) — canonical textbook
• Causal Inference: What If (2020) — canonical textbook
• Coefficient Alpha and the Internal Structure of Tests (1951) — empirical study
• Computer Science Curricula 2023 (CS2023) (2023) — professional standard
• Construct Validity in Psychological Tests (1955) — empirical study
• Define and solve a problem by using Solver — official vendor documentation
• Enhancing teaching through constructive alignment (1996) — empirical study
• Explicit instruction: Practice guide (2021) — professional standard
• Field Experiments: Design, Analysis, and Interpretation (2012) — canonical textbook
• Graphical Perception: Theory, Experimentation, and Application to the Development of Graphical Methods (1984) — empirical study
• Guidelines for Assessment and Instruction in Statistics and Data Science Education - College Report (2026) — professional standard
• Integer Programming (2020) — canonical textbook
• Introduction to Data Mining (2019) — canonical textbook
• Introduction to Lattices and Order (2002) — canonical textbook
• Introduction to Linear Algebra (2016) — canonical textbook
• Introduction to Linear Optimization (1997) — canonical textbook
• Introductory Econometrics: A Modern Approach (2020) — canonical textbook
• Investment Science (2013) — canonical textbook
• linprog: Solve linear programming problems — official vendor documentation
• MathML Core (2025) — professional standard
• Mostly Harmless Econometrics: An Empiricist's Companion (2009) — canonical textbook
• Nudge: Improving Decisions About Health, Wealth, and Happiness (2008) — canonical textbook
• Organizing Instruction and Study to Improve Student Learning (IES Practice Guide) (2007) — professional standard
• OWL 2 Web Ontology Language Document Overview (Second Edition) (2012) — professional standard
• Precalculus: A Prelude to Calculus (2024) — canonical textbook
• Principles of Corporate Finance (2020) — canonical textbook
• Principles to Actions: Ensuring Mathematical Success for All (2014) — professional standard
• Prospect Theory: An Analysis of Decision under Risk (1979) — empirical study
• Retrieval Practice Consistently Benefits Student Learning: a Systematic Review of Applied Research in Schools and Classrooms (2021) — empirical study
• Similarity matters: A meta-analysis of interleaved learning and its moderators (2019) — empirical study
• Standards for Educational and Psychological Testing (2014) — professional standard
• Statistical Inference (2002) — canonical textbook
• Statistical Theories of Mental Test Scores (1968) — canonical textbook
• The Description Logic Handbook: Theory, Implementation and Applications (2010) — canonical textbook
• The Design of Experiments (1935) — primary historical source
• The Elements of Graphing Data (1994) — canonical textbook
• The Elements of Statistical Learning: Data Mining, Inference, and Prediction (2009) — canonical textbook
• The Knowledge-Learning-Instruction Framework: Bridging the Science-Practice Chasm to Enhance Robust Student Learning (2012) — empirical study
• Thinking, Fast and Slow (2011) — canonical textbook
• Universal Design for Learning Guidelines version 3.0 (2024) — professional standard
• Web Content Accessibility Guidelines (WCAG) 2.2 (2024) — professional standard