Unit 5
[Listen and Write]
We know that dinosaurs once lived on earth from the fossils we have found. Fossils are the hardened remains of the ancient like forms that are found inside rocks.
When a dinosaur dies, its flesh rots away and only its skeleton remains. Over time heavy layers of mud and sand cover up its bones.
Millions of years later, the layers of the mud and sand harden to become sedimentary rocks. When it rains, water trickles through the rock, taking lots of minerals with it.
The minerals seep into the rocks and replace the bones of the dinosaurs. Over time, the minerals harden and take the shape of the bones they have replaced. The hardened minerals are what we call fossils.
Fossils help us learn more about the dinosaurs and other ancient life forms that once lived on earth.

[Memorized Dictation]
Some scientists study fossils to learn about the world in the past. First, they look for clues. Then, they gather evidence. Next, they search for information. After that, they examine their findings to discover new details. They figure out facts about the dinosaur from the details. They conduct experiments and do research to test and prove their ideas.