Fishtank Learning

3rd Grade Math
Unit 2: Multiplication and Division, Part 1
Lesson 1

Objective

Identify and create situations involving equal groups and describe these situations using the language and notation of multiplication.

Criteria for Success

Understand that equal groups are groups made up of equal numbers of objects in each group.
Understand that multiplication is the operation that tells you the total number of objects when you have a certain number of equal groups and use the multiplication symbol to represent equal groups (MP.2).
Understand that multiplication cannot be used to represent situations with unequal groups.
Understand that the way we write a multiplication equation is a convention where the first factor represents the number of groups and the second factor represents the size of the groups (MP.6).
Identify the number of groups, the size of each group, and the total number of objects in a context or picture of equal groups.
Understand that a factor is the number of groups or size of each group in a multiplication equation and the product is the total number of objects in a multiplication equation.

Warm Up

Choral Counting

Version 2: Skip-count by 2-5s and 10s

Anchor Tasks - Problem 1

a. Would you rather have Group A or Group B of Reese’s Pieces? Why?

Group A	Group B

b. Would you rather have Group A or Group B of Milk Duds? Why?

Group A	Group B

Guiding Questions

Would you rather have Group A or Group B of Reese’s Pieces? Why?
Would you rather have Group A or Group B of Milk Duds? Why?
When you have groups that all have the same number of objects in them, we call them equal groups. Are there equal groups of Reese’s Pieces? Of Milk Duds?
Does the color of the candies determine whether these are equal groups? What about other characteristics?
For Part (b), how many groups of Milk Duds are there? How many Milk Duds are in each group? How many Milk Duds are there in total?
Make 4 groups of 5 counters. Is this an example of equal groups? Why or why not?
Look at this picture. Is this an example of equal groups? Why or why not?

Notes

Students will need 20 counters for this task. Instead of presenting the pictures in the Anchor Task, you could also facilitate this task with physical objects in your classroom, e.g., actual candy, counters, etc., in which case you'll need a teacher set of those objects in addition to the counters for students.

Anchor Tasks - Problem 2

a. The $$2$$ groups of $$8$$ Milk Duds in Anchor Task 1 can be represented with the expression "$$2\times8$$," which we can read out loud as "two groups of eight," "two times eight," or "two multiplied by eight." We call this a multiplication expression whose factors are $$2$$ and $$8$$.

Using your counters, make $$6$$ groups of $$3$$. Then write a multiplication expression that matches your model.

b. The total number of objects in equal groups is called a product. So the product of $$2\times8$$ is $$16$$ since that's how many total Milk Duds there are. We can write a multiplication equation to represent this, $$2\times8 = 16$$.

What is the product in your model? Then write a multiplication equation that matches your model, including the product of it.

Guiding Questions

What multiplication expression did you write for Part (a)? What does the $$6$$ stand for? The $$3$$?
What is the product in your model? How can you modify your multiplication expression to be an equation including the product?
Let’s say we had the multiplication expression $$14\times27$$. What does the $$14$$ represent? The $$27$$? What is the product?

Notes

Students will need 12 counters for this task.

Anchor Tasks - Problem 3

Write a multiplication equation to represent the following picture.

Grid of squares divided into 3 rows and 3 columns, each row containing 3 squares of the same color.

Problem Set

View Problem Set

Discussion of Problem Set

Identify the factors and their meanings from each image in #1.
What did you notice about the answers to Parts (a) and (b) and Parts (c) and (d) in #1?
Which models were correct in #5? How do you know? Which models were incorrect? Why?

Target Task

For each image below,

Determine whether it has equal groups. Explain how you know.
If it does have equal groups, write a multiplication equation to represent it.

a. Circle divided into 4 equal parts, 3 parts shaded.

b. Group of cherries arranged in clusters, with varying numbers of cherries in each cluster.

Word Problem

Kai has 560 stickers. Kai has 230 more stickers than Margo. Margo got some more stickers for her birthday and now has 450 stickers. How many stickers did Margo get for her birthday?