# Colorful Building Arrays

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## Objective

SWBAT create arrays independently, generate addition sentences and then use the arrays to create a city picture

#### Big Idea

Ever think of a city street as an endless display of arrays? In this lesson students will begin to recognize how often our world is organized in arrays.

## Warm Up

10 minutes

I begin today's lesson with fluency practice in repeated addition. I orally dictate the following problems for students to solve:

2 + 2+ 2 =  ,        4 + 4+ 4 + 4 =,       5 + 5 + 5 =  The students record their responses in their math journals. I ask students how they solved the problems, and reinforce any students who suggested using arrays, or finding the doubles fact and then counting on. I know arrays are relatively new, but I am wondering if anyone has yet internalized the idea.

We discussed arrays in the previous lesson.  I ask students if they remember the word array? Who can show me an array somewhere in the room? Can you describe the array? (10 by 10 array for the number grid, etc.) I take several different suggestions from around the room.

I tell students that today we will be working with arrays.

## Independent Practice

20 minutes

Today I ask students to create some colorful arrays using squares of paper glued onto a larger sheet.

I model how to read the directions (build a 4 by 3 array), I take the colored squares and glue them on to make 4 rows with 3 in each row. I check that I have 4 rows and 3 in each row. I remind students to check their arrays before gluing the squares on and to remember that if they set down 4 to mark the rows, they already have 1 in each row so they only need to add 2 more in each row to get 3. Even when students say 4 rows of 3, they often forget that that first row they set up counts as one of the 3 in the row. It takes a little practice for students to remember that a 4 by 3 or 4 rows of 3 array should only have 3 in each row.

Below my array I write 3 + 3 + 3 + 3 = 12

I place a variety of 1 inch colored squares in the middle of each set of desks. I hand each child a large 12 x18)  piece of black paper. I hand each student a set of directions for making arrays. (I print off 3 different sets to allow for variety in the arrays that are created.) I check with the students to make sure they know that they must follow the directions, build the arrays and write the addition sentence below (above) the array.

I tell students to leave a little space between each array. They are welcome to have another large piece of paper if they fill up the first one. I give students about 15 minutes to build as many arrays as they can.

I walk around to make sure students understand how to build the array and create the math sentence from it. I help students who may be struggling with the concept.

## Creating Murals

15 minutes

I tell students that they will now work in small groups to create a city mural using their arrays, and adding city details to complete their murals.

I explain that they can cut out their different arrays, and use them to create buildings, city blocks, bus windows, street signs, etc. They are welcome to cut out other things (car wheels, streetlights, etc.) or to draw on their murals to complete the picture.

I let students choose their  groups of 4 students each, and ask them to take their arrays, and talk to their groups for 3 minutes about what they want to include in their pictures. They should agree on how to lay things out on the mural. I ask that the number sentences be glued on with the arrays.

At the end of 3 minutes I tell students they may begin their pictures. They will need to work together to complete their posters so we quickly review group work rules before beginning.

While students work on their murals, I circulate around the room providing support as needed.

An extension might be to ask a group to find the total value of their city by adding the total of all arrays. I would suggest this to a group that had worked quickly and grasped the concept of building arrays.

## Sharing

5 minutes

Students have a chance to stand up and share their murals with the rest of the class. I hang up the murals for others to see.