In this lesson, students create and solve problems related to scale and write and perform a scene to share their problems and solutions. Media resources and teacher materials are included.

Zooming In On Figures

Unit Overview

Type of Unit: Concept; Project

Length of Unit: 18 days and 5 days for project

Prior Knowledge

Students should be able to:

Find the area of triangles and special quadrilaterals.
Use nets composed of triangles and rectangles in order to find the surface area of solids.
Find the volume of right rectangular prisms.
Solve proportions.

Lesson Flow

After an initial exploratory lesson that gets students thinking in general about geometry and its application in real-world contexts, the unit is divided into two concept development sections: the first focuses on two-dimensional (2-D) figures and measures, and the second looks at three-dimensional (3-D) figures and measures.
The first set of conceptual lessons looks at 2-D figures and area and length calculations. Students explore finding the area of polygons by deconstructing them into known figures. This exploration will lead to looking at regular polygons and deriving a general formula. The general formula for polygons leads to the formula for the area of a circle. Students will also investigate the ratio of circumference to diameter ( pi ). All of this will be applied toward looking at scale and the way that length and area are affected. All the lessons noted above will feature examples of real-world contexts.
The second set of conceptual development lessons focuses on 3-D figures and surface area and volume calculations. Students will revisit nets to arrive at a general formula for finding the surface area of any right prism. Students will extend their knowledge of area of polygons to surface area calculations as well as a general formula for the volume of any right prism. Students will explore the 3-D surface that results from a plane slicing through a rectangular prism or pyramid. Students will also explore 3-D figures composed of cubes, finding the surface area and volume by looking at 3-D views.
The unit ends with a unit examination and project presentations.

Students further explore scale, taking a scale drawing floor plan and redrawing it at a different scale.Key ConceptsStudents explore change from one scale to another, focusing on the ratios. Students will draw a scale model of a house.GoalsRedraw a scale drawing at a different scale.Find measurements using a scale drawing.

Gallery OverviewAllow students who have a clear understanding of the content thus far in the unit to work on Gallery problems of their choosing. You can then use this time to provide additional help to students who need review of the unit’s concepts or to assist students who may have fallen behind on work.Problem DescriptionsSprinklersExplore different sprinkler layouts, looking at circular areas (and partial circles) to decide which will be best to water a lawn.Leaning TowerChoose a scale and use a ruler and protractor to make a simple scale drawing.Pizza DoublerIf you could choose between doubling the fraction of the pizza that a slice is, or doubling the radius, which option would give you more pizza? In this problem you will investigate which choice gives a bigger slice.Area and ScaleWhen a figure is redrawn at a larger scale the side lengths increase by the factor of the scale (if the scale doubles the size, the side lengths double also). But, does the area increase the same way? Explore a dynamic sketch and see how area changes when the scale changes.Tree House 1Given plans for a tree house, redraw the plans at a different scale.

Students will explore scale and use it to find measurements in scale drawings.Key ConceptsScale drawings are drawn proportionally so that there is a ratio between a given length on the drawing and the actual length. This ratio is used to set up a proportion to find other measurements.GoalsUnderstand that scale drawings are proportional.Use scale to find actual measurements.ELL: Define these terms in the context of the discussion:scalescale drawingscaled to fitproportionalAllow ELLs to use the dictionary if they wish.

Students learn and practice how to find the perimeter of a polygonal shape. Using a ruler, they measure model rooms made of construction paper walls. They learn about other tools, such as a robot, that can help them take measurements. Using a robot built from a LEGO® MINDSTORMS® NXT kit that has been programmed to move along a wall and output the length of that wall, students record measurements and compare the perimeter value found with the robot to the perimeter found using a ruler. In both cases, students sketch maps to the scale of the model room and label the measured lengths. A concluding discussion explores the ways in which using a robot may be advantageous or disadvantageous, and real-world applications.

This video tutorial [5:22] explores how objects are represented in a scale drawing to show they are similar. Assess learning with a quiz.

Scale drawings make it easy to see large things on paper. Watch this tutorial to learn all about them. [3:54]