WEBVTT

00:00:00.000 --> 00:00:05.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,0,160,90

00:00:05.000 --> 00:00:10.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,90,160,90

00:00:10.000 --> 00:00:15.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,180,160,90

00:00:15.000 --> 00:00:20.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,270,160,90

00:00:20.000 --> 00:00:25.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,360,160,90

00:00:25.000 --> 00:00:30.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,450,160,90

00:00:30.000 --> 00:00:35.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,540,160,90

00:00:35.000 --> 00:00:40.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,630,160,90

00:00:40.000 --> 00:00:45.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,720,160,90

00:00:45.000 --> 00:00:50.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,810,160,90

00:00:50.000 --> 00:00:55.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,900,160,90

00:00:55.000 --> 00:01:00.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-0.jpg#xywh=0,990,160,90

00:01:00.000 --> 00:01:05.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,0,160,90

00:01:05.000 --> 00:01:10.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,90,160,90

00:01:10.000 --> 00:01:15.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,180,160,90

00:01:15.000 --> 00:01:20.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,270,160,90

00:01:20.000 --> 00:01:25.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,360,160,90

00:01:25.000 --> 00:01:30.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,450,160,90

00:01:30.000 --> 00:01:35.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,540,160,90

00:01:35.000 --> 00:01:40.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,630,160,90

00:01:40.000 --> 00:01:45.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,720,160,90

00:01:45.000 --> 00:01:50.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,810,160,90

00:01:50.000 --> 00:01:55.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,900,160,90

00:01:55.000 --> 00:02:00.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-1.jpg#xywh=0,990,160,90

00:02:00.000 --> 00:02:05.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,0,160,90

00:02:05.000 --> 00:02:10.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,90,160,90

00:02:10.000 --> 00:02:15.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,180,160,90

00:02:15.000 --> 00:02:20.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,270,160,90

00:02:20.000 --> 00:02:25.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,360,160,90

00:02:25.000 --> 00:02:30.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,450,160,90

00:02:30.000 --> 00:02:35.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,540,160,90

00:02:35.000 --> 00:02:40.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,630,160,90

00:02:40.000 --> 00:02:45.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,720,160,90

00:02:45.000 --> 00:02:50.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,810,160,90

00:02:50.000 --> 00:02:55.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,900,160,90

00:02:55.000 --> 00:03:00.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-2.jpg#xywh=0,990,160,90

00:03:00.000 --> 00:03:05.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,0,160,90

00:03:05.000 --> 00:03:10.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,90,160,90

00:03:10.000 --> 00:03:15.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,180,160,90

00:03:15.000 --> 00:03:20.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,270,160,90

00:03:20.000 --> 00:03:25.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,360,160,90

00:03:25.000 --> 00:03:30.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,450,160,90

00:03:30.000 --> 00:03:35.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,540,160,90

00:03:35.000 --> 00:03:40.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,630,160,90

00:03:40.000 --> 00:03:45.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,720,160,90

00:03:45.000 --> 00:03:50.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,810,160,90

00:03:50.000 --> 00:03:55.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,900,160,90

00:03:55.000 --> 00:04:00.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-3.jpg#xywh=0,990,160,90

00:04:00.000 --> 00:04:05.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,0,160,90

00:04:05.000 --> 00:04:10.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,90,160,90

00:04:10.000 --> 00:04:15.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,180,160,90

00:04:15.000 --> 00:04:20.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,270,160,90

00:04:20.000 --> 00:04:25.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,360,160,90

00:04:25.000 --> 00:04:30.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,450,160,90

00:04:30.000 --> 00:04:35.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,540,160,90

00:04:35.000 --> 00:04:40.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,630,160,90

00:04:40.000 --> 00:04:45.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,720,160,90

00:04:45.000 --> 00:04:50.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,810,160,90

00:04:50.000 --> 00:04:55.000
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,900,160,90

00:04:55.000 --> 00:04:59.230
http://cdn.cs50.net/2014/segments/valve/thumbnails/valve-4.jpg#xywh=0,990,160,90