Pie Array Math Talk by Brenda Perez Hernandez

Math Lesson: 3rd Grade 

Lesson Goal: Students will be able to use multiplication to solve situations involving equal groups and arrays.  

1. Ask students to think about what kinds of foods they have seen in a refrigerated display case. Have a small discussion about this. 
2. Tell students they will have one minute, without talking to independently observe a work of art. Encourage them to write down observations and things they wonder about it.
3. Show the students Wayne Thiebaud’s painting called “Refrigerator Pies” for one minute. 
4. Bring the class back together. Point out the artist’s name and title of the painting. Wayne Thiebaud is famous for his paintings of tasty treats like pies, cakes, and candy.
5. Have a discussion about their notices and wonders and record them on chart paper or with sticky notes.  
6. Some students may bring up that there are 12 pies, acknowledge their answer and state that you will come back to their response.  
7. Ask students to independently and silently think about the following questions for two minutes: “How many pies do you see? How do you see them? After two minutes, let students turn and talk to share how many pies they saw and how they saw them.
8. Circulate the room to hear how students thought about the questions. Listen for these three different strategies that students can share with the whole group; 1.) counting each individual pie, 2.) repeated addition, 3.) multiplication.  
9. Ask students to explain how they arrived at the answer with each of the three strategies.  

Guiding Questions for Discussion:

• Tell me what you did. 

• How did you know there were 12 pies? 

• Why did you choose to repeatedly add 3 (or 4)? Where did you get 3 (or 4) from? 

• Where did you get the 3 or 4 from for your multiplication equation? 

• How is it that all of our different strategies led us to the answer of 12 total pies? 

Wisconsin Math Aligned Standard: M.3.OA.A.3: Use multiplication and division within 100 to solve word problems in situations involving equal groups, arrays, and measurement quantities, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem 

Indicators of mastery of the lesson:  

Developing: Student counts each pie individually to know how many pies total are in the image.  

Proficient: Student is able to use repeated addition to know the total number of pies in the painting (3+3+3+3). OR student is able to use knowledge of rows and columns of an array to identify that there are 4 rows and 3 columns. Student is able to use the knowledge of 4 rows and 3 columns to multiply 4 and 3 to find the total number of pies in the painting.