# 5mdc5a unpacked ```5.MD.C.5.A
*This standard is part of a major cluster
Standard
Relate volume to the operations of multiplication and addition and solve real world and mathematical
problems involving volume.
A. Find the volume of a right rectangular prism with whole-number side lengths by packing it with
unit cubes, and show that the volume is the same as would be found by multiplying the edge
lengths, equivalently by multiplying the height by the area of the base. Represent threefold whole
number products as volumes, e.g., to represent the associative property of multiplication.
* NOTE: In 5.MD.C.5.A students are NOT using the formula L x W x H, they are discovering the
formula.
Unpacked
Students learn to determine the volumes of several right rectangular prisms, using cubic centimeters, cubic
inches, and cubic feet. With guidance, they learn to increasingly apply multiplicative reasoning to
determine volumes, looking for and making use of structure. That is, they understand that multiplying the
length times the width of a right rectangular prism can be viewed as determining how many cubes would be
in each layer if the prism were packed with or built up from unit cubes. They also learn that the height of
the prism tells how many layers would fit in the prism.
Students might discover that the base of the prism is 2 x 3,
then multiply by the height (4).
Questions to check for understanding and increase rigor:
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How can you measure the volume of a container that is 5 &frac12; units x 2 ⅓ units x 1 &frac34; units? What is
the approximate volume of this container? Explain your strategy with both numbers and a model.
A cereal box has a volume of 128.8 cubic centimeters. What could the dimensions be?
Looking at the dimensions of two different boxes with identical volumes, what do you notice