*related topic: Research: Critical Thinking*

- Discrete Mathematics – Propositional Logic
Propositional Logic is concerned with statements to which the truth values, “true” and “false”, can be assigned. The purpose is to analyze these statements either individually or in a composite manner.

- forall x
An open access introductory textbook in formal logic.

- High School Mathematics Extensions – Logic
- Section describing the basics of mathematical logic and logical formulas from a free online textbook.
- How to Write Proofs
- A publicly-available section of a minicourse in mathematical reasoning and logic.
- Logic and Mathematical Statements
Self Test, Worked Examples, and Practice Problems

from the University of Toronto.
- Math and Logic Puzzles
- Sets of puzzles and solutions from the Math is Fun site.
- Mathematics | Introduction to Propositional Logic
Logic is the basis of all mathematical reasoning, and of all automated reasoning. The rules of logic specify the meaning of mathematical statements.

- Propositional Logic
As the name suggests propositional logic is a branch of mathematical logic which studies the logical relationships between propositions (or statements, sentences, assertions) taken as a whole, and connected via logical connectives.

- Study: Introduction to Logic (video)
- Series of videos from a Stanford professor on formal logic.