A1: Proof

From the DfE Mathematics AS and A-Level Content (LINK):

Introduction to Proof

A1-01 [Introduction to Proof]

A1-02 [Introducing Consequence and Equivalence]

A1-03 [Consequence and Equivalence Examples]

Proof by Exhaustion

A1-04 [Introducing Proof by Exhaustion]

A1-05 [Proof by Exhaustion Examples]

Proof by Deduction

A1-06 [Introducing Proof by Deduction]

A1-07 [Proof by Deduction Examples]

Disprove by Counter-Example

A1-08 [Introducing Disproof by Counter Example]

A1-09 [Disproof by Counter Example Examples]