1. 4/21 & 4/22- 7th Grade Agenda
Learning Objective: Discuss how radioactive dating can be used to date the age of rocks.
Collect HW: Reading & Notetaking p. 138 – 139
Video: Walking w/ Monsters before Dinosaurs
Textbook Reading: p
HW: Reading & Notetaking p.141 – 142

2. Reflection
Prompt: How can scientists know whether a rock is older than another rock?

3. What is an index fossil?
Index fossils help geologists match rock layer
To be useful as an index fossil, a fossil must be widely distributed and represent a type of organism that existed only briefly.

4. Which fossils are index fossils ?
Trilobite
Ammonite

5. These rocks are some of the oldest fossils in the world
These rocks are some of the oldest fossils in the world. How old are they?
Stromatolites: Remains of ocean reefs created by bacteria more than 3 billion years ago.

6. What is Radioactive Decay?
Radioactive Decay: over time, unstable elements break down or decay by releasing particles and energy.

7. What is half-life?
The half-life of a radioactive element is the time it takes for half of the radioactive atoms to decay.

8. If Geologic time went by in a single day, when did humans first appear?
Humans first appear one second before midnight

9. Geological Time Scale Paleozoic: Paleo means ancient or early
Mesozoic: Meso means middle
Cenozoic: Ceno means recent

10. Reflection
Prompt: Write 5 facts that you learned from the video.