Getting Started 
Misconception/Error The student does not consider the given conversion (7.5 gallons per cubic foot) when choosing a unit of measure for volume. 
Examples of Student Work at this Level The student chooses:
 A length measure such as inches, feet, or yards.
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 A volume unit other than cubic feet such as quarts, gallons, or cubic inches.
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 Feet but is unable to explain why this is the best choice.
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Questions Eliciting Thinking How is volume measured? Can it be measured in inches?
What does â€ś7.5 gallons per cubic footâ€ť mean? What is a cubic foot?
How would you calculate the volume of this tank?
If the volume of the tank were 10 cubic feet, how would you determine how much water the tank could hold?
If you were given that there are 67.5 gallons per cubic yard, would that change your choice of unit measure? 
Instructional Implications Review the concept of volume, the units of measure of volume, and how to calculate the volume of a rectangular prism. Guide the student to understand the conversion (7.5 gallons per cubic foot) and how it can be used to calculate the amount of water the tank can hold. Explain that in order to use this conversion, the volume of the tank should be calculated in cubic feet. Ask the student to calculate the volume of the tank (in cubic feet) and then use this value to calculate the amount of water the tank can hold. Ask the student to explicitly identify the units of measure used to represent the length, width, and height of the tank as well as the volume of the tank and the amount of water it can hold. Provide feedback.
Provide additional opportunities to reason about units in the context of problems and to solve problems involving multiple units of measure. 
Moving Forward 
Misconception/Error The student does not use units consistently when calculating volume. 
Examples of Student Work at this Level The student understands that in order to use the conversion, 7.5 gallons of water per cubic foot, volume must be measured in cubic feet. However, when calculating volume, the student does not use feet as the unit of measure. For example, the student calculates volume as:
 1 (yard) x 1(foot) x 18 (inches) = 18.
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 36 (inches) x 12 (inches) x 18 (inches) = 7,776.
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Questions Eliciting Thinking How did you determine the unit of measure for your volume calculation?
What unit did you use to measure length, width, and height? Does it make sense to use different units for each of these?
How many cubic inches are in one cubic foot? 
Instructional Implications Have the student consider finding the area of a 2 foot by 6 inch rectangle. Model the rectangle with a sketch drawn to scale. Partition the rectangle by dividing it into 1 foot by 1 inch sections. Ask the student to describe the dimensions of each section and determine if each section could be described as 1 square foot or 1 square inch. Explain that the length and width must be given in the same unit in order to measure the area using square units. Ask the student to further partition the rectangle into square inches and express the area in terms of square inches. Challenge the student to also express the area in terms of square feet.
Explain to the student that if the volume is to be expressed in cubic feet, then each of the dimensions of the tank should be expressed in feet. Ask the student to convert the length and the height to feet and recalculate the volume. Then ask the student to calculate the number of gallons of water the tank can hold and provide feedback.
Provide additional opportunities to reason about units in the context of problems and to solve problems involving multiple units of measure. 
Almost There 
Misconception/Error The student makes an error in calculating or describing the number of gallons of water the fish tank can hold. 
Examples of Student Work at this Level The student understands that in order to use the conversion, 7.5 gallons of water per cubic foot, volume must be measured in cubic feet and calculates the volume as 3 x 1 x 1.5 = 4.5 cubic feet. However, to determine the number of gallons the tank can hold, the student:
 Says the tank can hold 4.5 gallons of water.
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 Divides by 7.5 and says the tank can hold 0.6 gallons of water.
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 Multiplies by 7.5 but describes the volume as 33.75 cubic feet.

Questions Eliciting Thinking What is the unit of measure for your volume calculation? Is there one gallon of water per cubic foot of volume?
Why did you divide the volume of the tank by 7.5?
If you multiply 4.5 cubic feet by 7.5 gallons/cubic foot, what will be the unit of measure? 
Instructional Implications Model multiplying 4.5 cubic feet by 7.5 gallons/cubic foot as follows: . Explain how this calculation results in 4.5(7.5) gallons = 33.75 gallons of water.
Provide additional opportunities to reason about units in the context of problems and to solve problems involving multiple units of measure. 
Got It 
Misconception/Error The student provides complete and correct responses to all components of the task. 
Examples of Student Work at this Level The student understands that in order to use the conversion, 7.5 gallons of water per cubic foot, volume must be measured in cubic feet, and calculates the volume as 3 x 1 x 1.5 = 4.5 cubic feet. The student then multiplies 4.5 by 7.5 and concludes that the tank holds 33.75 gallons of water.
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Questions Eliciting Thinking Suppose a student calculated the volume of the fish tank as . How would you convert this measure to cubic feet? 
Instructional Implications Tell the student that a rough estimate for determining how many fish a tank can hold is to allow one gallon of water per inch of length of the fish (e.g., 5 gallons can support a fish whose length is 5 inches or five fish each 1 inch in length). Using this information, ask the student to calculate how many 3inch fish the tank can support.
Consider implementing MFAS task Notebooks to Trees (NQ.1.1). 