Ms. Shon's Spectacular Science
  • Blog
    • Unit 0: Scientific Inquiry
    • Unit 1: Earth as a System
    • Unit 2: Rocks and Minerals
    • Unit 3: Chemistry
    • Unit 4: Human Body Systems
    • IPW
  • Videos
    • Unit 0: Scientific Inquiry
    • Unit 1: Earth as a System
    • Unit 2: Rocks and Minerals
    • Unit 3: Chemistry
    • Unit 4: Human Body Systems
    • Ms. Shon's "Home" Videos
    • MS 88 in the Media
    • IPW
    • Cosmos: A Spacetime Odyssey (2014) >
      • Episode 3: When Knowledge Conquered Fear
  • Announcements & Homework
  • Links
    • Unit 1: Earth as a System
  • Glossary
    • Unit 0: Scientific Inquiry
    • Unit 1: Earth as a System
    • Unit 2: Rocks and Minerals
    • Unit 3: Chemistry
    • Unit 4: Human Body Systems
    • IPW
  • FAQ
  • Contact
  • Tests and Quizzes
  • Rubrics
  • For Teachers

Geologic Time Scale

12/2/2014

 
Picture
Scientists have organized the Earth’s 4,600 million year history (=4.6 billion history) into a massive timeline called the Geologic Time Scale (GTS).  The Geologic Time Scale is divided into huge time intervals that are further sub-divided into smaller time intervals.

Scientists have divided this timeline into huge “chunks”, or intervals, of time.  The largest "chunk" of time is known as the Supereon.  Supereons are broken down into smaller units of time called Eons. Eons are further divided into Eras, and Eras are divided into periods.  The “chunks” are all divided by huge events that end one and begin another.  

Since the Earth is so old, scientists describe most events in terms of “Million Years Ago” (MYA).

Picture
MYA = million years ago
1.  Cenozoic Era (65 MYA to present)
2.  Mesozoic Era (250-65 MYA)
3.  Paleozoic Era (544-250 MYA)
4.  Precambrian Eon (4600-544 MYA)

The Precambrian Supereon makes up the first 4 billion years of our planet’s history, which is almost 90% of the earth’s entire history!  The Precambrian Supereon began with the birth of the earth, and ended with an event called the “Cambrian Explosion”.  During the Precambrian Supereon, the atmosphere and oceans formed, and marine life originated.   We know this from fossils that date over 60 million years old. Some fossils include worms, jellyfish, corals, and other primitive invertebrates.

The Paleozoic Era began with the “Cambrian Explosion”, which was about 544 million years ago.  The “Cambrian Explosion” introduced a diversity of new marine life forms, as well as life forms on land.  The Paleozoic Era ended with the greatest extinction on earth caused by the impact of an asteroid 250 MYA.  

The end of the Paleozoic era brought on the beginning of the Mesozoic era, which was the era of dinosaurs and the first mammals!  During this time, the super-continent “Pangea” also began to break up.  The Mesozoic Era ended when a meteor hit the earth 65 MYA, killing many life forms, as well as making dinosaurs extinct. 

This event marked the beginning of the Cenozoic Era, which is the age of mammals, birds, bony fish and flowering plants. The Cenozoic Era began 65 million years ago and has not ended yet.  During this era, a number of mountain ranges were formed. Some of these were the Alps, Andes, and Himalayas. Along with mountain ranges, some volcanoes were formed. The animals and plants that we are familiar with today came in to existence during this period, including human beings.  

We humans are very new to planet earth.  The first human ancestor was on earth only 2 MYA, and the first modern human was on earth only 0.4 MYA!
Picture
Mr. Zimmerman at the Himalayan Mountains, which is a mountain range that formed when the Indian continent collided with the Eurasian continent during the Cenozoic Era.
Check out the following online interactive resources about the Geologic Time Scale:
  • BrainPop: Geologic Time (Username: ms881, Password: ms88rocks)
  • UCMP Berkeley: Understanding Geologic Time
  • National Geographic: Pre-historic Timeline
Assignment
See the questions on the Google Classroom stream/wall.

Scale Models in Science and Converting Units

2/12/2014

 
Scale Models in Science

Scientists often build and study models to better understand things that cannot be studied directly due to size (too big or too small), speed (too slow or too fast), and safety.  Models help scientists explain their findings and even help scientists to develop new questions.  Therefore, it is important that scientists build scale models that fairly represent the actual object under study.

What is a scale model?  A scale model is an enlarged or reduced representation of an object that has the exact same proportions as the actual object.  Maps and floor plans are great examples of scaled models (drawings), as is the typical plant and animal cell illustrations in textbooks and online.

Below (left) is a scale model of our Solar System.  Check out the video on the right to observe a model of our Solar System that is NOT scaled.
Picture
Converting Units

One of the most important skills scientists need to build a scale model is the ability to convert units.  In order to convert units, we must first find the scale factor/unit rate.  Scale factor/Unit rate is simply the relationship between two different units (scales).  All you need to find the scale factor/unit rate is a scale.  For example, 1 meter = 100 centimeters.  The scale factor would be 1/100 m/cm, OR, 0.01 m/cm.

We will use the following method to convert units:

1.  Find the scale factor (unit rate).
2.  Multiply the scale factor (unit rate) with the unit you want to convert.
3.  Cancel units.  There should only be one remaining unit.

**if you set it up right, the unit you want to convert TO should be left**
Example: Converting MYA to centimeters
The Earth's magnetic field was formed 3,500 MYA.   How would you convert this date to centimeters so that you can mark this event on a geologic time scale if the scale is 1 cm = 10 MYA? 

Let's walk through the 3 steps to find our answer:
1.  Find the scale factor (unit rate).
                                1 cm/10 MYA = 0.1 cm/MYA
2.  Multiply the scale factor (unit rate) with the unit you want to convert.                                 0.1 cm/MYA x 3,500 MYA = 350 cm
3.  Cancel units.  There should only be one remaining unit.
                                 In step 2, MYA was cancelled out because MYA/MYA = 1
Picture
Scale Model of Earth's Interior

Background
The Earth's interior is made up of 4 layers.  The outermost layer is called the crust, just like the outermost layer of bread.  The crust is made up of solid, lighter rocks that make up the continents and ocean floor. The mantle is the layer between the crust and the Outer core.  The mantle is made up of heavier, molten rock (aka magma) that is plastic (flows and moves), just like the lava that erupts from a volcano.  Beneath the Mantle is the outer core, which is made of liquid iron and nickel.  At the very center of the Earth is the inner core, which is made up of solid iron.  As you move closer to the center of the Earth, temperature and pressure increase. 

Holiday Homework Overview
Over the Mid-Winter Recess, you will be designing and building a scale model of Earth's Interior.  In order to do so, you will need to convert units from kilometers to centimeters.  This is because the Earth's layers are measured in kilometers (see above).  The unit conversions for each layer is the design/planning portion of the project.  Then you will use the converted measurements to start building your actual model.   With that said, complete the practice questions below to help you prepare to design and build a scale model!
Assignment
Copy the questions and answer them in complete sentences.  Make sure to title the assignment "Scale Models in Science and Converting Units".
Due: Friday, February 14, 2014

1.  Provide 3 reasons why the Solar System in the Jimmy Dean commercial (above) is not a scale model.
2.  The first humans are believed to have reached North America 0.13 MYA.  Convert this date to centimeters.  Scale: 1 cm = 10 MYA
3.  The Indian continent collided into the Asian continent approximately 50 MYA, creating the Himalayas.  Convert this date to meters.  Scale: 1 meter = 50 MYA 
4.  Convert 15.2 feet to inches.  Scale: 12 inches = 1 ft
5.  Convert 2500 milliliters to liters.  Scale: 1 L = 1000 mL
6.  How might you start designing your scale model of Earth's layers given the thickness of each layer (in picture above) if the scale were 1 cm = 6372.5 km?  Make your best guess using the same method for questions 2-5.
7.  Complete the form below.

    Archives

    January 2015
    December 2014
    February 2014

    Categories

    All
    Atmosphere
    Biosphere
    Continental Drift
    Convection
    Converting Units
    Density
    Earth
    Earth's History
    Earth's Interior Structure
    Geologic Time Scale
    Hydrosphere
    Lithosphere/Geosphere
    Mantle
    Mass
    Matter
    Meteorites/Meteors/Asteroids
    Models In Science
    Plate Tectonics
    Scaled
    Scale Factor/unit Rate
    Supernova
    Temperature
    Volume

    RSS Feed

Proudly powered by Weebly