Review: Factors

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Objective

SWBAT find factors of whole numbers by using a multiplication chart or calculators.

Big Idea

Knowing multiplication facts can make it easier to find factors of a whole number.

Whole Class Review

10 minutes

In review lessons, I like to use various strategies to revisit the skill.  Because it is a review skill, there is not a lot of conversation between the students.  The purpose of the review before the state test is to prepare the students to work independently in order to be successful on the end of year assessment.

 

In today's lesson, the students review finding factors of whole numbers.  This aligns with 4.OA.B4 because the students find all factor pairs for a whole number in the range 1-100. 

To begin the lesson, the students are called to the carpet to sit in front of the Smart board.  (I like for my students to be close so that I can make sure that all of them are being attentive.)  To review this skill, I show the students a video at the following site:

http://studyjams.scholastic.com/studyjams/jams/math/multiplication-division/prime-factorization.htm

After the video, I review briefly with the students.  On the Smartboard, I write the number 21. I remind the students that when finding factors, we can use patterns that we learned earlier.  For example, all even numbers are factors of 2, and 5 is a factor of any number that ends with a 0 and 5 in the ones place.  

I ask the students, "Is 21 an even number?"  The students know that 21 is not an even number.  I explain to them that because 21 is not an even number, 2 can not be a factor of 21.  I ask, "Does 21 end with a 0 or 5 in the ones place?"  The students know that 21 has a 1 in the ones place.  I explain to the students that 5 can not be a factor of 21 because it does not end with a 0 or 5.  I ask the students, "What multiplication sentences will give us 21?"  Student responses:  7 x 3, 3 x 7, 1 x 21, and 21 x 1.  I remind the students that we only need to write the factor one time when listing the factors of a number.  The factors of 21 are 1, 3, 7, and 21.

 

Independent Practice

15 minutes

The students will practice the skill independently because they will have to work alone for the state test.  Each student is given a Review Factors.docx.  They must solve the problem by using the multiplication chart or calculator.  In the Video - Reviewing Factors.mp4 of student work, you can see how the student solved the problems.

As the students work on the problems, I walk around to monitor their level of understanding.  If the students are having a difficult time, I will ask guiding questions to help lead the students to the answer.  

Possible Questions:

1.  What multiplication facts have a product of this number?

2. What patterns can be used to identify the factors?

3.  How does drawing arrays help solve the problem?

 

Any students having difficulty with the task will be grouped for intervention.

Share/Discuss/Analyze Solution

15 minutes

Upon completing the independent practice, I call the students back together as a whole.  I feel that it is very important to close out the lesson by sharing answers.  By doing this, it allows the extra opportunity to reach any students that still do not understand the concept.

I call on students to share their answers.  All students are not auditory learners; therefore, it is very important for the students to see the examples of work (Student Work - Factors).  I use my document camera to display the student work on the Smart board.  

Students are allowed to ask questions during this closing of the lesson.  The most important aspect for me is that I have identified any students that need 1-on-1 or small group remediation.