The Birthday Paradox explained and an interactive example included on the page.

Here is highly visual and useful page on permutations and combinations. The language is very informal.

Step One: Gentle intro

*“Are rational numbers countable?”*

Step Two: The Hotel Infinity

*“Related to Cantor’s argument that rational numbers are countable?”*

Step Three: Self Similarity

*“Can you write out details of constructing the Cantor Set?”*

A student mathematics resource in the form of a blog.