Counting (this leads into Probability ideas)
Dr. Richard Ruscyzk, founder of the Art of Problem Solving company and website (AOPS) and Dr. James Tanton both have produced many very interesting videos that explain a variety of counting and probability ideas. And you thought you had learned everything about counting in elementary school! I hope you enjoy these and learn a lot along the way! This is an area that is way underdeveloped in the usual mathematics curriculum for MS and HS. Below you will see a handful of videos which lead into a comprehensive look at probability, both algebraic and geometric. In general, look here for dozens of very good videos on Counting and Probability by Dr. Ruscyzk.
Counting Lists 1

Counting Lists 2

Venn Diagrams and the Principal of Inclusion/Exclusion

Venn Diagrams  3 Categories

Counting Independent Events 1

Counting Independent Events 2

Factorials 1

Factorials 2

Permutations 1  Order Does Matter

Permutations 2  Order Does Matter

Combinations 1  Order Does Not Matter

Combinations 2  Order Does Not Matter

Computing Combinations
