Global Logic and Reasoning Competition (GLRC)

Resources and Links

This page features several links to materials, web applications, organizations, and more. All of them can be used by ambassadors, teachers, and participants to get in touch with logic and reasoning and to sharpen their thinking skills.

Further resource collections: Presentations Lecture Notes

Math is Fun Puzzles

https://www.mathsisfun.com/puzzles/
"A large free collection of math and logic puzzles sorted by type and difficulty, from starter brain teasers to tricky algebra and logic problems. Every puzzle includes a clearly explained solution, making it a friendly entry point for building reasoning skills."

Brainzilla

https://www.brainzilla.com/
"A free site offering logic grid puzzles, zebra puzzles, riddles, and brain games playable directly in the browser. Puzzles are rated by difficulty, so you can start easy and work up to genuinely challenging deductions."

Puzzle Baron Logic Puzzles

https://logic.puzzlebaron.com/
"One of the largest logic grid puzzle sites on the web, with thousands of unique puzzles playable online or printable for pencil and paper solving. Timed play and statistics let you track your deduction speed against other solvers."

Simon Tatham's Portable Puzzle Collection

https://www.chiark.greenend.org.uk/~sgtatham/puzzles/
"A classic open-source collection of about 40 one-player logic games, including favorites like Slant, Loopy, and Pattern, all playable free in the browser. Puzzles are generated on demand with adjustable size and difficulty, so you never run out of practice material."

TED-Ed Riddles

https://ed.ted.com/lessons?category=riddles
"A series of short animated video riddles covering classic logic problems such as the prisoner hat riddle and the bridge crossing puzzle. Each video poses the problem, gives you time to think, and then walks through the reasoning behind the solution."

Puzzling Stack Exchange

https://puzzling.stackexchange.com/
"A question and answer community dedicated to creating, solving, and discussing puzzles of every kind, from riddles and lateral thinking to formal logic problems. Reading top-voted solutions is an excellent way to learn how experienced solvers structure their reasoning."

Cut the Knot

https://www.cut-the-knot.org/
"An encyclopedic collection of interactive mathematics miscellany including logic puzzles, probability paradoxes, proofs, and games, built up over decades by mathematician Alexander Bogomolny. Many pages include interactive applets that let you experiment with the ideas directly."

NRICH

https://nrich.maths.org/
"A free mathematics enrichment site from the University of Cambridge with thousands of rich problems designed to develop mathematical reasoning and problem-solving habits. Problems are organized by age level and many include hints, teacher notes, and published student solutions."

Your Logical Fallacy Is

https://yourlogicalfallacyis.com/
"A clean visual reference covering 24 of the most common logical fallacies, each with a plain-language definition and a real-world example. It is a quick way to learn to spot flawed arguments in debates, media, and everyday discussion."

Your Bias Is

https://yourbias.is/
"A companion site to Your Logical Fallacy Is that explains 24 common cognitive biases, such as confirmation bias and the anchoring effect, with clear examples. Understanding these mental shortcuts helps you recognize when your own reasoning is being led astray."

Logically Fallacious

https://www.logicallyfallacious.com/
"A searchable library of over 300 logical fallacies with definitions, logical forms, and worked examples for each. It functions as a comprehensive reference for anyone studying argumentation and informal logic."

Foundation for Critical Thinking

https://www.criticalthinking.org/
"The website of a long-established educational nonprofit offering a large free library of articles on the elements and standards of critical thinking. Its resources teach a structured framework for analyzing and evaluating reasoning in any subject."

Critical Thinking Web

https://philosophy.hku.hk/think/
"A free resource from the University of Hong Kong with over 100 tutorials on critical thinking, logic, fallacies, scientific reasoning, and creativity. It includes hundreds of exercises with answers, plus a famous collection of computer-generated knights and knaves puzzles."

Kialo Edu

https://www.kialo-edu.com/
"A free structured debate platform where arguments are organized into visual pro and con trees rather than chat threads. Mapping a controversy this way trains you to break complex questions into individual claims and evaluate each on its merits."

Brilliant

https://brilliant.org/
"An interactive learning platform with guided courses in logic, mathematics, probability, and computer science built around solving carefully sequenced problems. Its logic courses cover truth-tellers and liars, syllogisms, and strategic reasoning, with some content free and full access by subscription."

Khan Academy Statistics and Probability

https://www.khanacademy.org/math/statistics-probability
"Free video lessons and practice exercises covering probability, combinatorics, random variables, and statistical inference from the ground up. Mastery-based practice with instant feedback makes it a solid foundation before tackling probability puzzles and paradoxes."

Seeing Theory

https://seeing-theory.brown.edu/
"A visual introduction to probability and statistics from Brown University, built around interactive animations you can manipulate yourself. Chapters run from basic chance and expectation through Bayesian inference and regression, building intuition rather than just formulas."

The Evolution of Trust

https://ncase.me/trust/
"An acclaimed interactive explanation of game theory that lets you play and simulate the iterated prisoner's dilemma with different strategies. In about thirty minutes it teaches why cooperation succeeds or collapses, based on Robert Axelrod's famous tournaments."

Game Theory Online

https://www.game-theory-class.org/
"The home of the free game theory courses taught by professors from Stanford and the University of British Columbia, with full lecture videos, slides, and problem sets. It covers strategic games, Nash equilibrium, auctions, and mechanism design at an accessible level."

Art of Problem Solving

https://artofproblemsolving.com/
"The central hub for mathematical olympiad preparation, hosting a huge free wiki of contest problems and solutions plus active community forums. Nearly every top competition mathematics student in the English-speaking world uses its resources."

Evan Chen's Olympiad Problems and Solutions

https://web.evanchen.cc/problems.html
"A curated archive of national and international olympiad problems with solutions, maintained by an IMO gold medalist and USA olympiad coach. The linked handouts and advice pages teach the proof-writing craft that competition mathematics demands."

Project Euler

https://projecteuler.net/
"A famous series of hundreds of challenging problems that combine mathematical insight with computer programming. Solving one problem typically teaches a concept that unlocks the next, making it an addictive ladder for developing algorithmic reasoning."

Wolfram MathWorld

https://mathworld.wolfram.com/
"A comprehensive free encyclopedia of mathematics with thousands of entries on logic, set theory, probability, game theory, and recreational mathematics. Entries are cross-linked and include formal definitions, making it a reliable reference while solving problems."

Internet Encyclopedia of Philosophy

https://iep.utm.edu/
"A peer-reviewed free encyclopedia with accessible articles on logic, fallacies, paradoxes, and the philosophy of mathematics. Its entries are generally written at a level friendlier to newcomers than research literature, making it ideal for a first serious look at a topic."

Stanford Encyclopedia of Philosophy: Classical Logic

https://plato.stanford.edu/entries/logic-classical/
"The authoritative scholarly reference article on classical first-order logic, covering syntax, natural deduction, and model-theoretic semantics. It rewards careful reading and serves as a bridge from introductory logic to the professional literature."

Stanford Encyclopedia of Philosophy: Set Theory

https://plato.stanford.edu/entries/set-theory/
"A rigorous overview of axiomatic set theory, from the ZFC axioms and ordinals to the continuum hypothesis and large cardinals. It explains why set theory serves as the standard foundation for all of mathematics."

forall x: Calgary

https://forallx.openlogicproject.org/
"A free and open textbook on formal logic covering truth tables, symbolization, first-order logic, and Fitch-style natural deduction proofs. It is available as accessible HTML and PDF, includes exercises with solutions, and is used in university courses worldwide."

Stanford CS103 Truth Table Tool

https://web.stanford.edu/class/cs103/tools/truth-table-tool/
"A simple in-browser tool from Stanford's mathematical foundations of computing course that generates complete truth tables for any propositional logic formula. It accepts several notation styles, making it handy for checking homework and exploring tautologies."

Carnap

https://carnap.io/
"A free open-source platform for learning formal logic, with an interactive online textbook and automated checking of truth tables, symbolizations, and derivations. It gives instant feedback on your proofs, so you learn from mistakes immediately."

Natural Deduction Proof Editor and Checker

https://proofs.openlogicproject.org/
"A browser-based Fitch-style proof editor from the Open Logic Project that verifies natural deduction proofs line by line. It follows the system of the forall x: Calgary textbook, making it the perfect practice companion for learning to construct formal proofs."

Open Logic Project

https://openlogicproject.org/
"A collaboratively authored, freely licensed collection of advanced logic teaching materials covering first-order logic, model theory, computability, and incompleteness. Its texts fill the gap between introductory logic courses and graduate-level treatments."

The Natural Number Game

https://adam.math.hhu.de/#/g/leanprover-community/nng4
"A gamified introduction to formal mathematical proof in which you build the natural numbers from the Peano axioms using the Lean theorem prover. Across dozens of levels you prove real theorems about addition and multiplication, with the computer checking every step."