This Lesson has three parts. At the end of our Lesson, three videos by the Authors of your Textbook, if you wish to revise "scientifically! with a Harvard Professor.

PART 1

PART 2

PART 3

Pr. David BARTEL, part 1:

<iframe width="671" height="377" src="https://www.youtube.com/embed/dupzE66J8u4" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

part 2:

<iframe width="671" height="377" src="https://www.youtube.com/embed/TcZK_A_wcWQ" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Part 3:

<iframe width="671" height="377" src="https://www.youtube.com/embed/ACwOtzTiFQQ" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>