forallx: the Mississippi State edition is an open source logic textbook. It covers propositional logic, and it can be freely used or modified. The textbook is avaialbe as a PDF. Or a paperback copy can be purchased from this site. The source files are available in this GitHub repository.
This is the schedule that I use when teaching with the textbook.
|Weeks 1 & 2||forallx, chapters 1 & 2: introduction to arguments|
|Week 3 & 4||forallx, chapters 3 - 6: introduction to truth functional logic|
|Weeks 5 - 8||forallx, chapters 8 - 11: truth tables|
|Weeks 9 - 13||forallx, chapters 13 - 16: proofs|
|Week 14||forallx, chapter 17: theorems|
|Week 15||forallx, chapter 18: soundness and completeness|
|Exam week||Test 3|
Here is the syllabus.
Here is a more detailed calendar (for an online course).