In Unit 6, Three-Dimensional Measurement & Applications, students derive, describe, and use formulas for area and circumference of a circle, and volume and surface area of three-dimensional figures. In addition, students identify two-dimensional shapes that when spun around an axis will form a particular three-dimensional figure, identify cross-sections of three-dimensional figures, and analyze modeling situations.
In this unit, students build on their previous understanding of circles, volume, and surface area they developed throughout elementary and middle school to extend their reasoning into modeling situations, formula analysis, and deeper conceptual understandings. The primary foundational content students will need to have prior to beginning this unit are knowing the formulas for area and circumference of a circle from seventh grade; knowing the formulas for volume of a cone, cylinder, and sphere from eighth grade; and using Pythagorean Theorem from eighth grade and Unit 4.
The Unit begins with Topic A, Area and Circumference of Circles, where students refresh their understanding of area and circumference to solve problems. If students are proficient at these skills, the first three lessons may be skipped or combined. In Topic B, Three-Dimensional Concepts and General Volume, students build on their understanding of two-dimensional figures to develop an understanding of three-dimensional measurement and dimension through revolving two-dimensional figures around an axis, slices, and volume. Topic C, Cavalieri’s Principle, Spheres, and Composite Volume, explores Cavalieri’s principle with the purpose of comparing volumes of oblique and right figures and developing the underpinnings for the formula for the volume of a sphere, used in eighth grade Geometry. Topic C also challenges students to find the volume of nonstandard three-dimensional figures by adding or subtracting volumes of known figures. The unit concludes with Topic D, Surface Area, Scaling, and Modeling with Geometry, which focuses on modeling situations requiring the use of volume, surface area, density, rates, and unit conversions. Students are required to make general plans for the solution of problems, determine the measurements and formulas necessary to carry out these plans, evaluate the plans, and determine a final solution. The use of appropriate measurement is necessary for the estimates in this topic of the unit.
The material from this unit is foundational to applications in Algebra II and solids of revolutions through integration in Calculus.
Pacing: 20 instructional days (18 lessons, 1 flex day, 1 assessment day)