A Grain of Rice by Helena Clare Pittman

Mathematical Strand:

Algebra

Topic:

Students will solve the problem that comes up in the story. The students will realize the explosive growth of the powers of 2.

Grade level:

6-8

Lesson Created by:

Stacy Aschenbrenner Bergman Elementary, Manhattan, KS

Lesson Description

Materials

• Book—A Grain of Rice (There are similar versions of this book. The King's Chessboard by David Birch and The Raja's Rice by David Barry are just a couple. I chose this version because we are studying ancient China in Social Studies.)
  

1. Launching the lesson

1. Ask the students to think about this while I start reading the story. "Would you rather have $0.10 everyday for 10 days or would you rather get a penny on the first day and double that amount everyday for 10 days?
   
2. Read the story; stop at the part of the story when Pong Lo asks for a grain of rice. He wishes to double that grain of rice every day for one hundred days.
   

2. Developing the lesson

1. Go back to the question asked about the money. Tell the students that they are to figure out how much money they would receive, depending on the decision made.
   
2. Let the students share the answers.
   
3. Now give the students the task of figuring out how many grain of rice Pong Lo will have after 100 days. Let the students work with a partner.
   

3. Closure/Discussion/Elaboration

1. Discuss the answer.
   
2. Finish the story
   
3. Talk about what that much rice would look like. Where would Pong Lo put it all?
   
4. Have the students make a graph comparing getting $0.10 a day for 10 days to getting a penny on the first day and then doubling it everyday for 10 days.
   
5. Invite the students to create their own story related to the concept, powers of 2.