Fossils are like nature’s time machines. They are the remains or traces of plants and animals that lived a very long time ago. Most fossils form when a living thing dies and is quickly buried by sediment, like mud or sand. Over millions of years, layers of sediment build up, pressing down with great weight. Slowly, minerals from the water seep into the bones or shells, turning them into hard stone.
Not every animal becomes a fossil. Soft parts, like skin and muscles, usually rot away quickly. This is why most fossils we find today are hard parts like teeth, bones, and shells. However, sometimes we find "trace fossils." These aren't parts of the animal itself, but marks they left behind, such as footprints or burrows.
By studying fossils, scientists can tell what the Earth looked like long ago. For example, if a scientist finds a fish fossil in the middle of a dry desert, they know that the desert used to be covered by an ocean. Fossils also help us understand how animals have changed over time. Without fossils, we would never know that giant dinosaurs once roamed the very ground we walk on today.
According to the text “Stories in Stone,” why are teeth and shells more commonly found as fossils than skin or leaves?
In the text below, click the highlighted sentence that explains how a scientist might know a dry area was once underwater.
Based on the video “How a Fossil Forms,” what is the main purpose of the "sediment" that covers the animal?
Use information from the video to put the following stages of fossilization in the correct order (1-4).
Earth’s movement and erosion eventually bring the fossil to the surface.
A dinosaur dies near a riverbed and is quickly covered by mud.
Layers of sediment and heavy pressure turn the bone into mineralized stone.
The animal’s soft tissue rots away, leaving only the skeleton.
WRITING TASK
Consider what you have learned from the sources. You will now construct an original opinion paragraph using your own ideas. In your paragraph, answer the research question for the specific purpose and audience shown below.
Prompt: Why are fossils important for us to study today?
Purpose: To provide and support your opinion about the importance of fossils.
Audience: Your classmates and teacher
Be sure to give reasons for your opinion and support these reasons with information from the sources. Refer to the Writer’s Checklist as you write and edit your paragraph.
Prompt: Why are fossils important for us to study today?
Read this sentence from the text:
"Slowly, minerals from the water seep into the bones or shells."
If this happened a long time ago, which word should replace seep to show it is in the past tense?
Look at the sentence below. Click on the pronoun that replaces the noun "fossils.
" "Scientists study
Which sentence uses the correct verb to match the subject?
A scientist found three different fossilized tooth in the sand. What is the correct way to write the plural form of the word tooth?
In the sentence "The scientist felt great excitement when she found the T-Rex bone," which word is an abstract noun?
Choose the correct word to complete the sentence. The layers of mud built up (slow / slowly) over millions of years to create a (hard / hardly) rock.
hard
hardly
slowly
slow
Which of these is a compound sentence?
A student is writing a report about fossils. Which book title is capitalized correctly?
The fossil found today was than the one found yesterday.
Add the missing comma to the sentence below.
"Before the scientist moved the bone she took a photograph of it."
,