What's this?
It's a ruler
Who's this?
It's a teacher
What's this?
It's a computer
What's this?
It's chalk / It's some chalk / It's a piece of chalk
What's this?
It's a bag
What are they?
They're crayons
Who's this?
It's a student
What are they?
They're scissors
What's this?
It's a board
What's this?
It's a paperclip
What's this?
It's glue
What's this?
It's homework