Review: Expressions

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SWBAT evaluate expressions by using the four operations to find the missing number.

Big Idea

Expressions can be evaluated by replacing the variable with a number, then calculating.

Whole Class Review

15 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 evaluating expressions.  I remind students that a variable can be used in the place of more than one number or if the number is unknown.  This aligns with 4.OA.A3 because the students are representing  these problems using equations with a letter standing for the unknown quantity. 

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:

After the video, I display the following chart on the Smart board:














I tell the students that we can find the rule to the table by finding the pattern.  I tell the students to look at the numbers in the top of the table.  We have 21, 23, 25, and 27.  Next, I ask the students to look at the numbers at the bottom of the table.  I ask, "If the number went from 21 to 19, did the number go up or down?"  The students knew that the number went down.  I remind the students that if a number goes down then there are two operations to make a number go down.  I ask the students to tell me those two operations.  The majority of the class knew that division and subtraction makes a number get smaller.  I explained to the students that there is nothing we can divide 21 by to get a quotient of 19.  Therefore, the numbers in this table are being subtracted.  I told the students that we must figure out what number we are subtracting from the top row in order to get the bottom row. 

I ask, "What number can I subtract from 21 to get 19?"  I remind the students that we can "add on" from 19 to get back to 21 because addition is the inverse of subtraction.  The students all know that 19+ 2 = 21.  Therefore, we are subtracting 2.  I remind the students that we must make sure that this rule is correct for all of the numbers in the table.   After checking all of the numbers in the table, the students could see that the rule is s - 2.  


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 Expressions.docx.  They must solve the problem by using the four operations to find the rule to the table.  It is very important that the students show their work so that I can know they understand the skill.  In the Video - Reviewing Expressions.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 them to the answer.  

Possible Questions:

1.  What operation must you use to solve the problem?

2.  Did you work all of the problems in the table?

3.  What result did you get for each of the problems?


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 - Expressions).  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.