BYOD 9th Grade. ERAS

Hey there. Here is the a little bit different lesson on ERAS of Life on Earth, a little bit controversial but still worth studying.

Geological Eras

Learning outcomes: to be able to explain main events in plant’s and animal’s changes during life on Earth.

1. Step one (individual work): Circle the right words or phrases in italics to create grammatically correct questions.

Questions	Answers
1. How many years/old is the Earth?
2. What possibly could/might have created proto-continents?
3. When multicellular life could have possibly evolve/evolved?
4. Is it true/Is true that life on Earth began with single-celled prokaryotic cells?

Step 2 (individual work): Match the following correct answers to the questions above. There are two extra answers that cannot be used.

1. Yes, it is true. The history of life on Earth began about 3.8 billion years ago, initially with single-celled prokaryotic cells, such as bacteria.
2. Yes, there are.
3. Erosion, sedimentation and volcanic activity - possibly assisted by more meteor impacts - eventually created small proto-continents which grew until they reached roughly their current size 2.5 billion years ago.
4. There are 67000 of them.
5. The Earth is a little over 4.5 billion years old, its oldest materials being 4.3 billion-year-old zircon crystals.
6. Multicellular life evolved over a 1.5 billion years ago.

2. Step 1 (individual work): Read the text and circle words that you don’t  know.

Its earliest times were geologically violent, and it suffered constant bombardment from meteorites. When this ended, the Earth cooled and its surface solidified to a crust - the first solid rocks. There were no continents as yet, just a global ocean peppered with small islands. The continents have since repeatedly collided and been torn apart, so maps of Earth in the distant past are quite different to today's.

It's only in the last 570 million years that the kind of life forms we are familiar with began to evolve, starting with arthropods, followed by fish 530 million years ago (Ma), land plants 475Ma and forests 385Ma. Mammals didn't evolve until 200Ma and our own species, Homo sapiens, maybe only 200,000 years ago. So humans hypothetically have been around for a mere 0.004% of the Earth's history.

Step 2 (team work): Assemble the puzzle by matching time with what could happen at that time.