Lesson: Properties lesson 4
Lesson Objective
Lesson Plan
See plan for charts
I. Curriculum Standards
ü Count by 3 to 30 and 4 to 40, starting at any multiple of 3 or 4. [M.1.2.a]
ü Define multiplication as repeated addition. [M.11.2.a]
ü Explain the connection between multiplication and skip counting. [M.11.2.b]
ü Create arrays as models of repeated addition. [M.11.2.c]
II. The Point
What is an array?
III. Materials Needed
Copies of 2.10.4 Problem Solving Task
Optional: Enlarged Problem Solving Task
Math Journals/ Glue Sticks
12 counters per student
Slates and markers
Examples of reallife arrays: egg carton, box of pencils, sheet of stickers, Sudafed blister pack, etc.
IV. Lesson Outline
Time: 60 Minutes
5 min. – Understanding the point and the problemsolving task
5 min. – Independent problemsolving
30 min. – WholeClass Discussion/Practice/ Summary
10 min. – Slate Math
10 min. – Mental Math
V. Learning Activities
1. Understanding “the point” and the problemsolving task (5 min.)
Distribute a Problem Solving Task slip and 12 counters to each student.
Students try to read and understand the task independently. Provide support as needed as students retell the task to partners, the class, or themselves.
2. Independent problemsolving (5 min.)
Students use counters to solve the problem on their slates.
3. WholeClass Discussion/Practice/Summary (30 min.)
PART I – WholeClass Discussion
The Big Ideas:
ü An array is a rectangular arrangement of objects in rows and columns.
ü An array shows equal groups of objects.
ü Each row has the same number of objects and each column has the same number of objects.
ü Mathematicians describe arrays by saying how many rows there are and how many items there are in each row. (Model the language of ____ by ____arrays.)
ü We can show arrays with dots, squares, objects, etc.












2 by 6 arrays: 2 rows, 6 per row
2 x 6
6 + 6
ü The total number of objects in an array can be found using repeated addition, skip counting, or multiplication.
Possible Discussion:
Students share and discuss their responses to the problem.
ü You might place counters on the overhead or a magnetic surface so that they can be manipulated during the discussion to show the possible arrays.
ü As students suggest ways that the 12 desks could be arranged, ask students to find the total items in each array.
How many rows?
How many columns?
What would the addition sentence describes the array?
What would the multiplication sentence describes the array?
ü Students will most likely encounter the fact that each array can be shown two ways (2 x 6; 6 x 2). (Multiplication is commutative.) The number of rows and the number of desks in each row can be reversed.
Are these different arrangements?
[They will look different in a classroom, but it is important for students to realize that t they are the same arrangement turned sideways. You might demonstrate rotating an array 90º to help students see this. Since multiplication is commutative, the total amount in the array will not change if the number of rows and the number in each row are reversed.]









PART II – Whole Class Practice
Students practice:
a. describing arrays
b. arranging counters into arrays
c. drawing arrays
d. finding the total number of items in an array
a. Describing arrays
Hold up a reallife example of an array:
Create an array on the board or the overhead:
b. Arranging Counters in Arrays
Place your counters in an array that has:
5 rows
3 counters in each row
How many counters in all?
Write the multiplication number sentence.
c. Drawing Arrays
Draw an array that has:
4 rows
5 counters in each row
How many counters in all?
Write the multiplication number sentence.
Draw an array that has 8 dots.
How many rows?
How many dots in each row?
How many dots in all?
Write the multiplication number sentence.
PART III Summary
ü Stop and have students look back at the question that is The Point of today’s lesson.
ü Students work together with teacher to compose a statement that answers The Point’s question. Students record the statement into their journal as a summary of their learning from the lesson.
Example:
An array is a rectangular arrangement of objects in rows and columns.
Each row has the same number of objects and each column has the same number of objects.
ü Special Lifework: Ask each student to bring in a reallife example of an array over the next 23 days in order to create an Array Museum in your classroom. (You can tell students that if they cannot find an array, they can make one.)
4. Slate Math (10 min.)
Plan slate math/ counting practice according to students’ instructional needs.
5. Mental Math (10 min.)
Students participate in a Mental Math practice session.

Lesson Resources
2.10.4.doc 
40

2.10.4 Enlarged Task.doc 
48

2.10.4 Problem Solving Task.doc 
51
