# data[].attributes.attachment_link.title
Newton's Third Law of Motion 🏈 [Science of NFL Football]

# data[].attributes.attachment_link.title
Newton's Second Law of Motion 🏈 [Science of NFL Football]

# data[].attributes.attachment_link.title
Newton's First Law of Motion - Science of NFL Football

# data[].attributes.attachment_link.title
Mitosis: The Amazing Cell Process that Uses Division to Multiply! (Updated)

# data[].attributes.attachment_link.title
Phases of the cell cycle (article) | Khan Academy

# data[].attributes.attachment_link.description
If you're seeing this message, it means we're having trouble loading external resources on our website. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

# data[].attributes.attachment_link.description
The security system for this website has been triggered. Completing the challenge below proves you are a human and gives you temporary access.

# data[].attributes.attachment_link.description
Learn about conservation of energy with a skater gal! Explore different tracks and view the kinetic energy, potential energy and friction as she moves. Build your own tracks, ramps, and jumps for the skater.

# data[].attributes.attachment_link.description
Pigeonetics [Internet]. Salt Lake City (UT): Genetic Science Learning Center; 2014 [cited 2019 Aug 16] Available from https://learn.genetics.utah.edu/content/pigeons/pigeonetics/

# data[].attributes.attachment_link.readable_text
Relative age means the age of one object compared to the age of another object. Relative age does not tell the exact age of an object. The relative age of rocks and fossils can be determined using two basic methods: ordering of rock layers and index fossils:
Ordering of Rock Layers

Complex layering due to intrusions and extrusions, faults, or unconformities can make dating rocks and fossils challenging. How do scientists accurately determine the age of rocks and fossils when each of these factors occur?

Radioactive element decay can also be used to tell the age of fossils and rocks. How does this process work? Is it reliable? Why or why not?

Scientists read the rock layers knowing that each layer is deposited on top of other layers.

The law of superposition states that each rock layer is older than the one above it. So, the relative age of the rock or fossil in the rock or fossil in the rock is older if it is farther down in the rock layers.

Relative dating can be used only when the rock layers have been preserved in their original sequence.

Index Fossils

Certain fossils, called index fossils, can be used to help find the relative age of rock layers. To be an index fossil -

an organism must have lived only during a short part of Earth's history;

many fossils of the organisms must be found in rock layers;

the fossil must be found over a wide area of Earth;

the organism must be unique.

The shorter time period a species lived, the better an index it is.

Fossils that are found in many rock layers, therefore living long periods of time, do not qualify as index fossils.

# data[].attributes.attachment_link.description
Relative age means the age of one object compared to the age of another object. Relative age does not tell the exact age of an object. The relative age of rocks and fossils can be determined using two basic methods: ordering of rock layers and index fossils: Ordering of Rock Layers Complex layering due to intrusions and extrusions, faults, or unconformities can make dating rocks and fossils challenging.

# data[].attributes.attachment_link.readable_text
My first job is to find the fossils . Fossils are found in layers of sedimentary rock . So that's where the team and I go—to places with sedimentary rock. They could be as close as Arizona or as far away as the Gobi Desert in Mongolia!

At the dig site we begin by looking for exposed fossils. When we find something we start digging. We dig slowly and carefully so we don't damage the specimen. Back in the lab, we can study the fossil more closely. Our goal is to determine what kind of animal it was and when it lived.

Want to find out how the history of life is written in the rocks? Let's go!

# data[].attributes.attachment_link.description
My first job is to find the fossils . Fossils are found in layers of sedimentary rock . So that's where the team and I go-to places with sedimentary rock. They could be as close as Arizona or as far away as the Gobi Desert in Mongolia!

# data[].attributes.body
Click on this link to log into the student book. You will need to sign in with your school username and password.