Naming Multiplication

Strategies2.2

Warm Up This number is less than 50 This number is not a factor of 100 This number of tiles will make only one

rectangle. Work with your partner to come up with

possible answers.

Naming Strategies Now we are going to explain our solutions. As we

look at each poster, try to name the strategy after seeing the first step.

If you are explaining a strategy, your job is to help us follow your steps and to use your story or picture to explain how you are keeping track of the parts.

If you are listening to someone else’s strategy, your job is to listen carefully, try to understand the strategy being explained, and compare it with your own strategy. Ask questions if you need a clearer explanation.

Let’s review our posters: 35 x 28 Which of these representations were the

same? Which are different? Are there any representations that seem

particularly clear to you? Are there ways we can use shortcuts in our

representations?

Guiding Questions What are some strategies you can use to

solve multiplication problems?

Jason received $10.00 each time he took out the trash. He took the trash out twice a week. After 5 months, how much money would Jason have?

A. $50.00B. $500.00C. $400.00D. $100.00

The maintenance crew is responsible for cleaning 208 windows. Each window has 15 panes of glass. How many panes does the crew have to clean?

A. 3,210B. 3,120C. 3,010D. 2,920

Which of these is not a factor of 80?A. 8B. 3C. 10D. 20

Objective Today, you’re going to practice using

different multiplication strategies to solve 2 digit problems. We will work on 2 different kinds of arrays!

Guiding Question: What are some strategies I can use to solve multiplication problems?

Arrays 20 8

35

28

35 x 28

35 x 20 = 700

Let’s think about teams. Its field day, and all the teams need to line up in the field to make a huge rectangle. There are 35 teams with 28 students on each team. The problem is to figure out how many students there are on all of the teams. So if we start with 35 x 20, who can explain what 35 times 20 means in terms of the teams? What part of the problem have we solved? What else do we need to do?

1 way array

2 way Array 20 8

30

28

35 x 28

30 x 20 = 600

30 x 8 = 240

5 x 8 = 40

35

5 x 20 = 100

5

U.S. Algorithm 29 x 16

Let’s Practice! Allie had 38 orders for bouquets. Each

bouquet uses 19 flowers. What is the total number of flowers needed to fill the order.

Justin Book Fair There are 27 book fair shelves in the

Library. Each shelf has 54 books on it. How many books are in the book fair?

Challenge! There were 48 teachers present at the

staff meeting yesterday after school. The meeting was held in the Art room. There were 8 tables available in the Art room. How many teachers were seated at each table?

Problems Involving Teams There are 37 teams and 28 students on each

team. How many students are there? There are 68 teams at the tournament. Each

team has 16 players. How many players are at the tournament?

There are 49 teams in the football league. Each team has 28 players. How many players are there?

There are 57 teams entered in the relay race on Field Day. Each team has 32 people. How many people are entered in the relay race?

There are 44 teams and 35 people on each team. How many people are on the teams altogether?

Independent Assignment Select THREE of the five problems below

and solve using any strategy you choose. Show your work, using CLEAR and CONCISE notation.

27 x 19 42 x 32 76 x 8 82 x 56 65 x 14

Guiding Questions What are some strategies you can use to

solve multiplication problems?