# Lesson: Equations: Multiplication using Variables

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### Lesson Objective

SWBAT solve multiplication equations with variables (letters or pictures)

### Lesson Plan

Materials Needed: DN Worksheet (to be cut in half), white board, dry erase markers, IND worksheet (doublesided)
Vocabulary: multiplication, operations, equations, variables, signal words

……….

Do Now (3 -5 min): Each student is handed half of the worksheet and asked to complete it independently. The worksheet reviews inequalities.

Opening (2 -3 min): Teacher says, “Yesterday, we learned about using variables in subtraction word problems. So far we have learned about inequalities and using variables in subtraction and addition problems. Today we are going to work on setting up and solving multiplication equations. To be successful at this independently we need to follow the same two rules: 1) Signal Words that tell us it is a multiplication problem and 2) setting up the equation to solve. By the end of this lesson, you will all be able to set up and solve one-step multiplication equation with variables. Are there any questions?”

Direct Instruction (10 – 12 min): Teacher then writes the following equation on the board x * 7 = 56 and says,  “I will be using a little star for our multiplication sign today, since our variable is x. Watch as I solve this equation using the algebraic process. It will mirror the process for addition and subtraction problems, only I will have to rely on my multiplication and division fact knowledge.”

Step 1: Write out equation as is x * 7 = 56
Step 2: Get the variable by itself x = 56 ÷ 7
Step 3: Solve for the variable x = 8
Step 4: Check variable answer 8 * 7 = 56
56 = 56

Teacher then continues, “Alright, did everyone see how I did that? It is the same process we have be using for the last two days. However, who can tell me something I could have done if I didn’t know the answer to 56 ÷ 7? [Count up the number of 7s in 56, Add 7 until I reach 56, use a multiplication chart] Those are all great answers, which  show me that you all are understanding division. Now let me practice this with a word problem. The steps will be the same even though it is a word problem, so I will leave them on the board so we can use them as reminders. When we tackle a word problem we have to do more than just solve the equation. We have to determine the variable, set up the equation, and then solve. Watch as I do this one.”

The teacher writes the following problem on the board and then works through with these steps:

Example 1: Mom gave you \$ 7 last week for helping out with your little brother. This week, you are going on vacation, so she gives \$28 dollars to travel. What would 7 be multiplied by to get  \$28?

Teacher should reference the Which Operation Chart. Be sure to point out the link between the signal words for addition and multiplication. Teacher should ask the students

Step 1: Write out equation x * 7 = 28
Step 2: Get the variable by itself x = 28 ÷ 7
Step 3: Solve for the variable x = 4
Step 4: Check variable answer 4 * 7 = 28
28 = 28

Teacher then continues, “Now, lets look at how this question. You will see questions like this on the DC-CAS. More than likely the questions only ask you to set up the equation. However, they will call it a number sentence. We know that an equation is a number sentence. So who can tell me what the number sentence was to solve this problem? [x * 7 = 28]. Very good!”

Guided Practice (8 -10 min): Teacher then completes Example 2 for guided practice. An additional problem can be added if students are having difficulty.

Example 2: The tickets to see the Jay-Z costs 4 times more than that to see Chris Brown. If the ticket to Jay-Z is \$120, how much does it cost to see Chris Brown?

Step 1: Write out equation x * 4 = \$120
Step 2: Get the variable by itself x = \$120 ÷ 4
Step 3: Solve for the variable x = 30
Step 4: Check variable answer 30 * 4 = \$120
\$120 = \$120

Example 3: You had brought home 3 bottles of water from the corner store. Mom wants you to bring 30 water bottles home. How many more times the original number is that?

Step 1: Write out equation x * 3 = 30
Step 2: Get the variable by itself x = 30 ÷ 3
Step 3: Solve for the variable x = 10
Step 4: Check variable answer 10 * 3 = 30
30 = 30

Independent Practice (10 min): Teacher gives each student their own copy of the Independent Practice (IND) worksheet. Teacher circulates the room to answer individual student’s questions.

Closing (2-3 min): Teacher calls the attention of the students back toward the front of the class to quickly review the answers to the Independent Practice worksheet/ ask what we learned about.

### Lesson Resources

 IND_lesson 5 side 2.pdf IND Lesson 5 side 1   Classwork DN Lesson 5   Starter / Do Now 1