Logistic regression (Shalizi, 2012) [mandatory, see below which parts]
A more mathematical (compared to our lecture), but still friendly explanation of logistic regression. Read the first 6 pages, that is, section 12.1 and the (complete) section 12.2. You don't have to know the formulas, but you need to understand their meaning.
(This is Chapter 12 from Advanced Data Analysis from an Elementary Point of View. Download the draft from the author's site while it's free.)