Zearn Math Grade 5, Mission 5: Addition and Multiplication with Volume and Area
In this unit, your child finds volume by packing rectangular prisms with unit cubes, then by multiplying length × width × height, and adds the volumes of joined boxes. They also find the area of rectangles with fractional side lengths, like 2 1/2 by 1 1/2, by tiling and by multiplying. It builds on fraction multiplication and leads into problem solving on the coordinate plane.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Mission 5?
- Describing volume as the number of unit cubes that pack a solid with no gaps or overlaps. Learn more: Volume: how much space is inside a solid
- Measuring volume by counting cubic centimeters or cubic inches in layers, including cubes hidden from view. Learn more: Finding volume by counting cubes
- Using V = l × w × h and V = B × h to find volumes, and adding the volumes of two boxes put together. Learn more: Finding the volume of a box
- Finding the area of a rectangle with fractional sides, like 2 1/2 by 1 1/2, by tiling it with unit squares and by multiplying. Learn more: Multiplying fractions, like 2/3 × 4/5
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
Hana stacks 12 unit cubes into a tall tower. Then she takes it apart and uses all 12 cubes to build a long, low wall. How does the volume of the wall compare with the volume of the tower?
- They have the same volume
- The tower has more volume
- The wall has more volume
How you can help
- Build an L-shaped figure from blocks or dice, made of two boxes side by side. Ask your child to find each box's volume and add them.
- Measure a placemat, a cutting board, or a book cover to the nearest half inch. Ask your child to find its area by multiplying the mixed numbers.
- Compare two food boxes from the pantry, measuring each in inches. Find the volume of each, and see whether the taller box really holds more.
Where kids can get stuck
- Using the whole shape's length for one part when splitting an L-shaped figure, so some cubes get counted twice.
- Assuming the taller box always holds more, when a short, wide box can have a greater volume.
- Multiplying only the whole-number parts, so a 3 1/2 by 2 rectangle gets an area of 6 instead of 7.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- volume
- The amount of space inside a solid shape, measured in cubic units.
- unit cube
- A cube that is 1 unit long, 1 unit wide, and 1 unit tall.
- cubic unit
- The unit for measuring volume: the space one unit cube fills.
- rectangular prism
- A solid shape with six rectangle faces, like a box.
- base
- The bottom face of a solid; its area times the height gives the volume.
- height
- How tall a solid is, from the bottom to the top.
- area
- The number of square units that cover a flat shape.
- mixed number
- A whole number and a fraction together, like 2 1/2.
Want to help your child master volume and area?
In Bobby's Math Club, your child practices these skills at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free.
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Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
Which math standards does Zearn Math Grade 5 Mission 5 cover?
Zearn Math Grade 5 Mission 5 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.