Text lesson

Unit 4 — Dating Planet Earth

Science — Third Preparatory

Common mistakes

Comparison aspect	Main idea	Keywords
Writing the units of the geologic time scale in the wrong order.	Remember: Eons (largest) Eras Periods Epochs (smallest). A helpful phrase: "Every Elephant Pushes Eggs"	RememberEonslargestEras
Mixing up mold and cast.	The mold is the hollow impression the cast is the solid copy that fills it	hollowimpressionsolidcopy
Thinking that analogous structures prove a common ancestor.	They do not they show adaptation to similar functions. Homologous structures are the ones that point to a common ancestor	showadaptationsimilarfunctions
•	Saying that half of the sample disappears in one half-life and all of it in two. After two half-lives one quarter is left not zero the amount never reaches exactly zero but becomes too small to measure after many half-lives	Sayinghalfsampledisappears
•	Forgetting that a mass extinction is an event not a cause of the appearance of new species. Mass extinctions remove many species geographic isolation mutation and natural selection explain the appearance of new species	Forgettingmassextinctionevent
Confusing the fossil record with the rock record.	The fossil record is all the fossils found the rock record is the sequence of rock layers and formations. Scientists use both together	fossilsfoundsequencelayers

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The lesson’s question bank is split across the points above; each point has its own questions underneath.
To work through the whole bank on one page:

Unit 4 — Dating Planet Earth · 23 / 28

Common mistakes