52×10=520 and 52×4=208. The sum of 520 and 208 is 728.
14×50=700 and 14×2=28. The sum of 700 and 28 is 728.
Using algorithms:
Lesson 6
What’s the Quotient?
Divide like a Pro
Here are two different ways to start finding the value of 8,435÷7. Choose one way and complete the calculation.
Find the value of 1,038÷6. Try to use as few steps as possible.
Show Solution
1,205. See sample response.
173. See sample response.
Lesson 7
Solve Multiplicative Comparison Problems
Restaurant Budget
In 2023, the cost of a meal for two people in a mid-range restaurant is about $75 in the United States. A similar meal in Ghana is about $37.
Write a statement that compares the cost of a meal at a restaurant in the United States to a meal in Ghana and uses the phrase “. . . times as much as . . . .”
A couple wants to spend only $350 at restaurants each month. How many more times could the couple go out to a restaurant each month if they eat in Ghana rather than in the United States? Show or explain your reasoning.
Show Solution
Sample response: A meal at a restaurant in the United States costs about 2 times (or twice) as much as a meal in Ghana.
3 more times. Sample response: In the United States: 4×75=300, which is less than 350. They could eat at a restaurant 4 times. There will be $50 extra. In Ghana: 9×37=333. They could eat out 9 times and have $17 left.
Lesson 8
Solve Problems with Multiplication and Division
To and Fro
In one week, a train made 8 round trips between its home station and Union Station. At the end of the week, it traveled a few more miles from the home station to a repair center. That week, the train traveled a total of 1,564 miles.
Which statement is true for this situation? Explain or show your reasoning.
The distance traveled for each round trip is 200 miles. The distance to the repair station is 26 miles.
The distance traveled for each round trip is 193 miles. The distance to the repair station is 8 miles.
The distance traveled for each round trip is 8 miles. The distance to the repair station is 1,500 miles.
The distance traveled for each round trip is 195 miles. The distance to the repair station is 4 miles.
Explain why one of the choices could not be true.
Show Solution
D. Sample responses:
1,560−4=1,560, 1,560÷8=195
195×8=1,560, 1,560+4=1,564
Sample responses:
I know A could not be true because I know 200×8=1,600 and that’s more than the total distance the train traveled.
I know C could not be true because the situation says it's just a few more miles to the repair center. 1,500 miles is not a few more miles. (8×8)+1,500 does match the total distance, but it doesn’t match the situation.
Lesson 9
Create Word Problems
A Music Festival
The school band wants to raise $1,700 for a music festival. They have raised $175 each week for the past 6 weeks.
Write a question that could be asked about this situation and answer it. Show your reasoning.
Show Solution
Sample response:
Question: If the band keeps raising $175 each week, how many more weeks before it reaches its goal?
Answer: 4 weeks. In 6 weeks, the band raises $1,050, so it still needs to raise $650. Three more weeks mean an additional 3×175 or $525. So one more week would mean 525+175 or $700.
Lesson 10
Estimation Exploration
Reflection
Describe something mathematical that you understand better after completing today’s activities, or something that you find confusing or challenging.
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Sample response: After multiplying several numbers multiple times to make estimates, I understand much more that there are different ways to break apart and rearrange the factors to make it easier to find products. Usually I’d just multiply the numbers in the order they were given.
Lesson 11
Which Three Go Together
Reflection
As mathematicians, it is important to explain our thinking and listen to the reasoning of others.
Describe a time today when you learned something new, or thought differently about something, based on what a classmate said.
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Sample response: In one of the Which Three Go Together? one set showed only numbers. I realized that which group of numbers went together was based on the digits being used. My group helped me see that we also could look at place value, whole numbers versus decimals, and whether the digits are odd or even.
Lesson 12
Number Talk
Reflection
As mathematicians, we often use patterns to help us reason about new problems. Observing something that repeats over and over can also help us solve problems.
Describe a time, during today’s lesson or recently, when you noticed a pattern or a repetition and used it to help you think through a problem. How did the pattern or repetition help you?
Show Solution
Sample response: Recently, I noticed that one way to find the product of a whole number and a fraction, like 81, is to divide the whole number by the denominator of the fraction. When I multiply 16 by 81, the result is the same as the result of dividing 16 by 8. I have used this observation to check my answers to multiplication problems like this.