Instructional Video5:50
Professor Dave Explains

Methods of Dating the Earth Part 1: Relative Dating

12th - Higher Ed
We've learned about all the enormous time spans that describe the billions of years in Earth's history, but how did we arrive at these dates? How can we know the age of the Earth? Let's learn about some dating methods, starting with...
Instructional Video5:36
Professor Dave Explains

Radiometric Dating: Carbon-14 and Uranium-238

12th - Higher Ed
When you read about the ages of certain ancient artifacts, or even the age of the earth itself, how do we know such numbers? How can we know that a fossil is precisely 250 million years old? The key technique here is radiometric dating....
Instructional Video
Khan Academy

Khan Academy: Measuring Age on Earth: Chronometric Revolution

9th - 10th
Discussion of the relatively recent changes in our ability as a species to shine light on our deep past. [9:53]
Instructional Video
Khan Academy

Khan Academy: Lebron Asks: If Earth's History Is a Basketball Game When Were Humans

9th - 10th
LeBron James asks Sal about how long humanity has been around as compared to the history of the Earth. [8:08]