NOTE: iPad with dad & only laptop available w/o typing. Today we continued our lesson on Life on Earth. We learned of the 4 major eras: Precambrian, Paleozoic, Mesozoic, & Cenozoic. The Paleozoic is made of 7 periods & was 2nd longest. We then learned of the Great Extinction. Most of the amphibians & any ocean life were wiped out. Lastly, we gained knowledge of Precambrian time. There are no fossils b/c there are no rocks/way to tell how old it is, but is estimated to have lasted 4 billion years