Proportional Relationships and Unit Rates

Mrs. Lopez teaches Grade 8 students about representing proportional relationships with equations, focusing on the equation y = kx. She explains how to find the constant of proportionality by dividing y by x. The lesson includes a practical example comparing corn prices at two stands, using unit rates to determine the better price. Students learn to write equations for each stand and complete tables with calculated values. The lesson concludes with a reminder to complete homework.

What is the general form of the equation used to represent proportional relationships?

• y = x/k

• y = k - x

• y = x + k

• y = kx

How can the constant of proportionality be determined?

• By multiplying y by x

• By dividing y by x

• By adding y and x

• By subtracting x from y

If a stand sells 6 ears of corn for $1.50, what is the price per ear?

• $0.30

• $0.25

• $0.20

• $0.15

Which stand offers a better price per ear of corn?

• The stand selling 6 ears for $1.50

• The stand selling 13 ears for $3.12

• Both stands offer the same price

• Neither stand offers a good price

What is the equation for the stand selling 6 ears of corn for $1.50?

• d = 0.30x

• d = 0.24x

• d = 0.25x

• d = 0.20x

How many ears of corn can be bought for $50 at the stand with a unit rate of $0.25 per ear?

• 180 ears

• 150 ears

• 200 ears

• 208 ears

What is the constant of proportionality for the stand selling 13 ears for $3.12?

• 0.20

• 0.30

• 0.24

• 0.25

How many ears of corn can be bought for $50 at the stand with a unit rate of $0.24 per ear?

• 150 ears

• 200 ears

• 180 ears

• 208 ears

Why might a consumer choose the stand with a slightly lower unit rate when buying in bulk?

• It has a wider variety of corn

• It is closer to their location

• It results in significant savings over large quantities

• It offers a better quality of corn

What activity is planned for the next class according to the conclusion?

• A quiz on the lesson

• A guest lecture on agriculture

• A field trip to a corn farm

• A card sort activity