Here you will find a model of a linear relationship between two quantities, the water depth of a channel and the distance across the channel at water level. The cross section of the channel is the shape of an isosceles trapezoid. The function is as the distance across the channel (d) increases the water depth (y) increase. It is up to your class to graph this function and determine what the slope and vertical intercept means. The commentary extends the task by asking how much water is flowing down the channel. If your scholars know the area of a trapezoid and are able to look up the velocity of water this would make a great extension. But the resource has enough algebra content without including the extension.

Concepts

functions, linear relationships, linear

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Additional Tags

linear relationship, function, rate of change in functions, math

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Pros

• Good model of a linear relationship between two quantities
• Real-life model of slope and vertical intercept
• Strong use of math vocabulary

Cons

• The text may be difficult for some learners
• More discussion questions are needed
• No additional practice

Common Core

8.F.B.4 MP4