This task is from Tools for NC Teachers. Students consider a mathematical claim about how to find the volume of a rectangular prism. This is remixable. 

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Bennett and Seth are having an argument about the formula for finding the volume of a rectangular prism.  Bennett says that to find volume you have to know the length, height, and width of the figure. Seth says that you only need to know the base and height of the figure. 

Which student do you agree with?  Why?  Write an expression that shows each boy’s formula for finding volume.

Draw a rectangular prism and label it with dimensions.  How would Bennett find the volume of this prism?  How would Seth find its volume?