Understanding Direct Proportion

The video tutorial explains the concept of direct proportion, focusing on how to relate two variables using a 'magic number'. It demonstrates the process of finding this number by dividing a pair of known values and using it to complete a table of values. The tutorial includes examples with different variables, illustrating both forward and reverse calculations. The lesson concludes with a final example and encourages students to practice independently.

What is the first step in understanding direct proportion between two variables?

• Subtract the smaller variable from the larger one

• Divide the variables by a constant

• Calculate the sum of the variables

• Identify the variables and their relationship

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CCSS.7.RP.A.2B

How do you determine the 'magic number' in a table of directly proportional variables?

• By adding the values of x and y

• By dividing one known pair of x and y

• By subtracting y from x

• By multiplying x and y

If x is directly proportional to y, and the magic number is 7, what is y when x is 4?

• 28

• 21

• 35

• 14

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CCSS.HSA.REI.A.1

In the example with variables p and q, what operation is used to find q from p?

• Divide by 5

• Multiply by 5

• Add 5

• Subtract 5

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CCSS.HSA.REI.A.1

What is the reverse operation when finding p from q in the example with variables p and q?

• Multiply by 5

• Add 5

• Divide by 5

• Subtract 5

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CCSS.3.OA.A.1

In the second example, what is the result of multiplying 20 by the magic number 6?

• 100

• 120

• 140

• 160

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CCSS.5.OA.B.3

What is the correct operation to find the top value from the bottom value in the second example?

• Subtract 6

• Divide by 6

• Add 6

• Multiply by 6

What should you do if you are unsure about the direction of calculation in direct proportion?

• Always divide

• Check the direction and use the opposite operation

• Guess the operation

• Always multiply

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CCSS.5.OA.B.3

What is the magic number if 30 is divided by 5 in the final example?

• 4

• 5

• 6

• 7

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CCSS.8.F.A.1

CCSS.HSF.IF.A.1

What is the value of y when x is 6, given the magic number is 6?

• 12

• 1

• 36

• 6

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CCSS.8.F.A.1

CCSS.HSF.IF.A.1