A Shell Built From Ribs

In the picture

1. 1The spine running down the middle of the opened shell
2. 2A rib curving outward and merging into the shell wall
3. 3The shoulder blade sitting outside the human ribs

Examples

• Your own ribs, which are part of your skeleton and move when you breathe
• A crab’s hard shell, which is its skeleton on the outside

Quiz: A Shell Built From Ribs (Age 10)

1. 1

   Which sentence explains why a turtle can never step out of its shell?

   • Its shell is made from its own bones and is part of its body.
   • Its shell is tied on with strong strings.
   • Its shell is a little house with a door that locks.
2. 2

   What did a turtle’s ribs do to help build the shell?

   • They grew wide and joined together.
   • They stayed short and floated inside the body.
   • They turned into separate plates that can slide apart.
3. 3

   Which statement about a turtle’s shell is true?

   • It is part of the turtle’s skeleton, not something it carries.
   • It is a separate house that the turtle can leave.
   • It is a soft covering that can be shed like a jacket.

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.