Linear Orders and the Real Line

Definitions of dense linear orders (with/without endpoints), separable linear orders, complete linear orders, the countable chain condition for linear orders, a Suslin line/Suslin tree and Suslin's problem Statement and proof of Cantor's Theorem characterizing (Q,<) as the only countable dense linear order without endpoints, up to isomorphism, the corollary which characterizes (R,<) as the only separable complete dense linear order without endpoints, every countable linear order embeds into (Q,<) (and thus, into (R,<)). Explanation of why Suslin lines and Suslin trees are equivalent, what an Aronszjan line/tree is, how it's a weakening of a Suslin line/tree. History and independence of Suslin's problem.