Grade 3
Lesson: 7-4
Reference to English
Problem Solving:
Choose an Appropriate Equation
Math Standard(s): 3.OA.4 also 3.OA.6
Domain: Operations and Algebraic Thinking
Content objective(s):
Language Objective(s):
Students will solve word problems by writing equations that
Students will write, read and explain story problems with their
represent the problem situations.
partner.
I can solve word problems by writing equations that represent
I can write, read and explain story problems with my partner.
the problem situations.
Essential Understanding:
Required Academic Vocabulary for Word Wall:
Frequently word problems can be solved by writing equations
Listen:
that represent the quantitative relationships involved.
Read:
Write:
Speak:
Sentence Frame:
Materials:
 Whiteboards, erasers, markers
Additional Lesson Vocabulary:
Lesson:
Instructional Time: 30 minutes
Opening: (7 minutes)
 Pass out whiteboards, erasers and markers.
T: “You know how to solve problems involving addition, subtraction, multiplication, and division. Quick review…write an
addition problem on your board and solve it.”
S: will write an addition problem on their board and solve it.
T: “Show me your boards.”
T: “Well done. Now write a subtraction problem on your board and have your neighbor solve it.”
S: will write a subtraction problem on their board and their neighbor will solve it.
T: “Please read the subtraction sentence to your neighbor.”
S: will read the subtraction sentence they wrote to their neighbor.
T: “Please write a multiplication problem on your board and solve it.”
S: will write a multiplication problem on their board and solve it.
T: “Show me your boards.”
T: “Lastly, please write a division problem on your board and tell your neighbor a story problem that uses it.”
S: will write a division problem on their boards, then they will tell their neighbor a story problem that uses the division problem
written on their board.
T: “Raise your hand if you think your neighbor had a great story problem…Tell me their story problem.”
S: will tell the class their neighbors story problem.
T: “Today you will use what you know about these operations to write equations to show problem situations.”
T: “Tell you neighbor how you would solve this word problem.”
T: “In gym class, 21 students were placed in 3 groups of equal size. How could you find how many students were in each group?”
S: will tell their neighbor how they would solve the problem.
T: “How did you choose to solve the problem?”
S: will respond.
T: “That is one way to solve the problem, did anyone have another way?”
 Listen to the different ways students will solve the problem. Make sure they use division, multiplication, repeated addition…)
Introduction to New Material (Direct Instruction): (6 minutes)
T: “I am going to read a problem aloud.”
T: “Kenny was asked to hand out 24 crayons equally to the 4 people at his table. Please write the important information on your
whiteboard.”
S: will write the important information on their whiteboards.
 Teacher also needs to write 24 crayons and 4 people on the whiteboard.
T: “Please write the division number sentence that goes with the story so far.”
S: will write 24 divided by 4 =
T: “Yes, we both wrote 24 divided by 4 equals. Today we are going to add a letter. We are going to add the letter ‘n’. The letter
‘n’ will stand for the number of crayons each person would get. In the equation you have already written, write ‘n’ where it
belongs.”
S: will write ‘n’ in their equation.
T: “Does yours look like mine? n = 24 divided by 4? Or 24 divided by 4 = n?”
S: will check their work.
T: “Today you are going to use what you know about division, multiplication, addition and subtraction to write equations to
show problem situations.”
T: “Can you think of a multiplication problem that uses the same numbers? Write it on your board.”
S: will write a multiplication problem that uses the same numbers.
T: “Show me your board. Good job. 6 X 4 = 24. Can you write an addition problem?”
S: will write an addition problem with the same sum.
T: “Show me your boards. Yes, 4 + 4 + 4 + = 24. Well done!”
 Make sure students understand why each of the accepted equations is correct. Point out how each one of them shows
everything that is know about the situation and the relationship among the quantities.
 Repeat the process with additional problems, mixing in problems that, as a group, will elicit from the students equations using
all four operations.
Guided Practice: (6 minutes)
Use the modeling cycle:
All Students Do:
T: “Now it is your turn to create your own story problem. I want you to write your story problem on a piece of paper and have
your partner read it and solve it. You will need to write the equation that goes with the story problem.”
S: will write a story problem.
T: “You have 1 more minute, and then your need to give it to your partner to read and solve.”
T: “Now, give your problem to your partner.
S: will read and solve each other’s problems.
T: “Now I want you to turn to your partner, read the equation you wrote and explain how you solved their problem.”
S: will turn to their partner and explain how they solved their problems.
T: “Please turn in your problems with both names on it and come back to the carpet with your whiteboard.”
Closing: (8 minutes)
T: “We are going to do 3 more problems together. I will read them and I need you to tell me which answer is correct from the
ones written on the board.”
 Write the following answers on the board. A. 10 / 2 = n, B. n = 10 X 2, C. 10 – 2 = n, D. 10 + 2 = n.
T: “Problem #1 – Omar exercise 10 hours each week. He exercises 2 hours each day. How many days does Omar exercise each
week?”
T: “Write the important information on your board and solve the problem.”
S: will solve the problem.
T: “Which of the equations on the board is correct for this story problem?”
S: will respond.
T: “Why? Tell your neighbor.”
S: will tell their neighbor why they think a certain answer is correct.
T: “Why?”
S: will tell the class why they think a certain answer is correct.
 If the students don’t choose the correct answer with the right reasoning, go over it with the whole class.
 Continue with 2 more problems.
o Carl delivers 56 newspapers each morning. He has already delivered 18 papers. How many papers does he have left to
deliver?
 A. 56 + n = 18, B. 56 – 18 = n, C. n = 56/18, D. 18 X n = 56.
o A patchwork quilt has 3 rows of squares in each row. How many quilt squares are in the quilt?
 A. 3 + 5 = n, B. 3 + n = 5, C. 3 X 5 = n, D. 5/3 = n
Assessment:
Story problems.