People
This
Numbers
That
Places
100

The name of Petra and Calder's teacher.

Who is Ms. Hussey?

100

The items Calder keeps in his pockets. 

What are pentominoes?

100

The number of people who received the mysterious letter.

What is three?

100
The author of "Lo!".

Who is Charles Fort?

100

The name of the bookstore where Calder works.

What is Powell's?

200

The name of the kid missing in Tommy's neighborhood. 

Who is Frog?

200

The name of the book found by Petra at Powell's.

Lo!

200

The number of Pentominoes in a set. 

What is 12?

200

The inspiration behind Petra's Halloween costume.

What is a dream?

200

The location of Petra and Calder's middle school building.

The University of Chicago

300

The name of the previous owner of the book, "Lo!".

Who is Mrs. Sharpe?

300

The name of the painting that Calder and Ms. Sharpe have in common. 

What is The Geographer?
300

The number of Vermeer paintings that Calder and Petra found with the lady in the yellow jacket.

What is 3?

300

Petra and Calder saved and savored one of these to signify secrecy and breakthrough in their investigation.

What are blue M & M's? 

300

The location of the Petra and Calder's field trip with Ms. Hussey. 

What is The Art Institute?

400

The person who received a mysterious letter. 

Who is Petra's dad?

400

Calder's Halloween costume

What the letter F pentomino?

400

This number represents Calder's birth month and his upcoming age. 

What is 12?
400

They created a list of unexplained stuff

Who are Petra and Calder?

400

The location where Petra and Calder learn the "A Lady Writing" is being kept. 

What is The National Gallery in Washington, D.C.?

500

The artist who said, "art is the truth that tells a lie".

Who is Picasso?

500

According to Charles Fort, these fell from the sky during a thunderstorm.

What are frogs?

500

The period of time Vermeer was alive.

What are the 1600s?

500

Petra finds this in the weeds of Calder's yard. 

What is a letter?

500

Calder's best friend Tommy moved here.

What is New York?