Minds On
Beach cleanup
On the shores of Lake Ontario, litter builds up and ends up falling into the lake.
Julio and Georges were walking on the path along the lake and noticed there were a lot of pop cans building up along the lakeshore. They decided to clean up the shore and returned to their car to get garbage bags.
Julio and Georges determined that they can fit 55 pop cans in each bag.
When they finished cleaning up the shore, they had filled 8 bags in total.
How may pop cans did Julio and Georges collect in total? Show your thinking using a method of your choice.
When you are ready, press the 'Answer' button to reveal the correct answer.
In this activity, you will practice using an array and matrix to multiply 3-digit numbers and 2-digit numbers with a 1-digit number.
Action
Lunch rewards
Dr. Martin Luther King Jr. Public School has 328 students in their junior classes.
As a prize for winning an art competition, all 328 junior students received a pizza lunch for free. Each student ordered 4 slices of pizza. How many pizza slices did the pizzeria have to make for the 328 students?
The Grade 7 and 8’s helped with the competition, so they were included as well. All 98 students decide to order 2 slices of vegetarian pizza. How many vegetarian slices did the pizzeria need to make?
Let’s think about our pizza problem some more.
There are 98 grade 7 and 8 students who ordered vegetarian pizza. Using the matrix strategy, we know 98 is 9 tens plus 8 ones or 90 plus 8.
Each of the 98 students ordered 2 slices of vegetarian pizza. Multiply to get 196.
The pizzeria needed to make 196 vegetarian slices.
We can use the same matrix strategy for a 3-digit number multiplied by a 1-digit number. Recall that each of the 328 junior students ordered 4 slices of pizza. For the 328 junior students, we can use place value to express 328 in expanded form: 300 + 20 + 8.
328 is formed with 3 hundreds (value 300), 2 tens (value of 20), and 8 ones (value of 8). Now we need to multiply each of these numbers by 4 and add these together to determine the total number of pizza slices.
The pizzeria had to make 1,312 slices for the 328 junior students, with each student ordering 4 slices.
But what about the Grade 7’s and 8’s?
How many slices were needed including both the junior students and the intermediate students?
When you are ready, press the 'Answer' button to reveal the correct answer.
Consolidation
Cleaning up the plastic beach
For Earth Day, 328 junior students at Martin Luther King Jr. Public School decided to participate in a shoreline cleanup. Each student was challenged to fill four (4) garbage bags during the cleanup.
How many garbage bags did the junior students fill in total?
The Grade 7s and 8s also asked to help out with the shoreline cleanup. All 98 Grade 7 and Grade 8 students filled 2 garbage bags each! How many bags of garbage did the Grade 7s and 8s fill in total?
We can use the same matrix strategy for a 3-digit number multiplied by a 1-digit number. Recall that each of the 328 junior students filled 4 garbage bags. For the 328 junior students, we can use place value chart to express 328 in expanded form: 300 + 20 + 8.
328 is formed with 3 hundreds (value 300), 2 tens (value of 20), and 8 ones (value of 8). Now we need to multiply each of these numbers by 4 and add these together to determine the total number of garbage bags filled.
The junior students filled 1,312 garbage bags in total. What about the Grade 7s and 8s?
How many garbage bags did the junior students and the Grade 7s and 8s fill altogether?
When you are ready, press the 'Answer' button to reveal the correct answer.
Reflection
As you read through these descriptions, which sentence best describes how you are feeling about your understanding of this learning activity? Press the button that is beside this sentence.
I feel...
Now, record your ideas using a voice recorder, speech-to-text, or writing tool.
Press 'Discover More' to extend your skills.
Discover MoreThere are great garbage patches floating in both the Pacific Ocean and the Indian Ocean. There are millions of pieces of garbage floating in these patches. Find out more information about these phenomena and explore the different ways that scientists are trying to solve this problem.
How might this garbage affect the wildlife in the ocean?