1. Module 6
Lesson 9

2. Objective
Solve word problems involving addition of equal groups in rows and columns.

3. Get the Ten Out and Subtract
For every number sentence I give, subtract the ones from ten. When I say 12 – 4, you say 10 – 4 = 6. Ready?
12 – 8.
13 – 7.
Now let’s add back the ones.
12 – 8. Take from ten.
Now add back the ones.
12 – 8 is…?
True or false: = 12 – 8?
Practice taking the ten out of number sentences fluently before adding the ones back.
Continue with the following possible sequence: 13 – 7, 11 – 8, 13 – 9, 15 – 7, and 14 – 8.

4. Core Fluency Practice On your mark, get set, THINK!
Time for 2 minutes.

5. Happy Counting by Tens: Crossing 100
Let’s count by tens, starting at 160. Ready?
Excellent! Try it for 30 seconds with your partner, starting at Partner B, you are the teacher today.
Point up rhythmically until a change is desired. Close hand to indicate a stopping point. Point down to count in the opposite direction. Continue, periodically changing direction.
Example: 160, 170, 180, 190, 200, 210, 220, 230, (Switch.) 230, 220, 210, 200, (Switch.) 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, (Switch.) 410, 400, 390, 380.

6. Concept Development
Problem 1: Anu wants to know how many eggs are in the carton. She sees 4 eggs in both rows. How many eggs are there?
Read the problem aloud.
Draw to show Anu’s eggs.
What number sentence should we write to find the total?
What did you draw?
Read your statement to your partner.
Materials: Personal white boards

7. Concept Development
Problem 2: Miss Tam arranges desks into 4 rows of 5. How many desks are in her classroom?
Draw a picture to solve and write a number sentence. Then write a statement of your answer.
Read the problem aloud.
Draw to show Miss Tam’s desks.
How many desks are in each column, or unit?
Write that unit of 4 at the bottom of each column.
So, what number sentence could we write to find the total?
So, what number sentence could we write to find the total?
Circulate as students draw.

8. Concept Development There are 20 desks in Miss Tam’s room.
Turn and talk, how could we represent this problem using a tape diagram?
Great! Let’s build our tape diagram together.
Let’s represent the first row of desks. How many units are inside?
Yes, and how many in the second part?
Yes, and how many in the third part?
Yes, and how many in the last part?
Remind me, why are there 4 parts to our tape diagram?
Yes, our tape diagram is just another way to represent the problem. It’s a great problem-solving strategy!
Write a number sentence under your tape diagram and a statement of your answer. When you are writing your statement, be sure to check the original question. What is your statement?
You’re on a roll! Let’s represent this next problem using only a tape diagram. Here we go….
Problem 2: Miss Tam arranges desks into 4 rows of 5. How many desks are in her classroom?
There are 20 desks in
Miss Tam’s room.

9. Concept Development
Problem 3: Yehuda ate 4 cherries each in the morning, afternoon, and evening. How many cherries did Yehuda eat altogether?
Read the problem aloud.
Draw a tape diagram to show the cherries Yehuda eats.
How did you draw your tape diagram?
What number sentence should we write to solve?
Share your statement with your partner.
Circulate as students draw.
If students need more practice, create simple word problems using subjects that lend themselves to the drawing of arrays, e.g., window panes, muffin tins, flower beds.