What are some events that all of us have had in our lives? Ask the class "What are some events that all of us have had in our lives?" Make a list of 5 or 6 things on the board. Let’s organize these!
Earth’s history spans 4.54 billion years, and scientists use the geologic time scale to divide it into eons, eras, periods, and epochs. By studying rock layers, fossils, and isotopes, they can ...