Minds On
Lunch party
A group of friends were getting together to have lunch. One friend brought 4 plates filled with equal amounts of carrot sticks and celery sticks. How many carrot sticks and celery sticks might be on each plate? Each plate has to have the same number of vegetables on them. How many carrot sticks and celery sticks were brought to the lunch altogether?
What you did is create groups to multiply.
Multiplication involves repeated equal groups, so one of the numbers you gave refers to the number of objects in a group, and the other number refers to the number of groups. Now we are going to look at different groups of objects and create a multiplication equation for them.
Let’s explore the following picture! There are two circles with three dots in each.
- How many groups of dots are there?
- How many dots in each group?
- What would our answer be altogether? How did you find this out?
When we are multiplying, we are doing repeated addition. We would write 3 + 3 = 6.
Examine the following picture where we have three groups with two dots in each group.
How many groups of dots are there?
- How many dots in each group?
- How many dots are there altogether? How did you find this out?
- What will our repeated addition look like for this picture?
Our last picture shows us three groups with 3 dots in each.
How many groups of dots are there?
- How many dots in each group?
- How many dots are there altogether? How did you find this out?
- What will our repeated addition look like for this picture?
When we multiply, we use the number of groups, multiplied (×) by, the number of objects in each group. For example, here we would write: 3 × 3 = 9.
Action
Activity – Cupcakes at a party
How many equal groups would you need to make to show one half of 12 cupcakes? 20 cupcakes? 24 cupcakes?
Find as many different ways as possible to equally share the cupcakes. How many people can you equally share the cupcakes with? How many cupcakes will each person get?
We will have a group with 12 cupcakes.
We will have another group with 20 cupcakes.
And our last group will be sorting 24 cupcakes.
How many equal groups can you put your cupcakes in?
You can use your notebook to complete this activity and record the different equal groups you can make with the cupcakes.
Student Success
Think-Pair-Share
One half and one quarter
- How many different equal groups could you make with 12 cupcakes? 20 cupcakes? 24 cupcakes?
- How many equal groups would you need to make to show one quarter of 12 cupcakes? 20 cupcakes? 24 cupcakes?
Note to teachers: See your teacher guide for collaboration tools, ideas and suggestions.
Consolidation
Activity
Follow these three activities for the number 16:
Activity 1: How can you skip count to reach the number 16?
Activity 2: How can you use repeated addition to reach the number 16?
Activity 3: How can you make equal groups that total 16?
Multiplication strategies
First, let’s review these multiplication strategies with examples:
Skip counting
In order to figure out the product of 5 and 4, we can skip-count 4 groups of 5 – 5, 10, 15, 20 or 5 groups of 4 – 4, 8, 12, 16, 20.
Repeated addition
Multiplying numbers can be thought of as adding a number to itself repeatedly. For example, to figure out the problem 3 x7, we could add 7+7+7 or 3+3+3+3+3+3+3 to make 21.
Equal groups
Multiplication means “equal groups of” and is represented with a multiplication sign: ‘×.’ For
example: 3 × 6 can be read as 3 equal groups of 6.
Reflection
How do you feel about what you have learned in this activity? Which of the next four sentences best matches how you are feeling about your learning? Press the button that is beside this sentence.
I feel...
Now, record your ideas about your feelings using a voice recorder, speech-to-text, or writing tool.