Unit 3: Similarity

Time Frame:  20 Days

 

 

Math > Grade 7 > Unit 3

 

Unit Description

This unit introduces the concept of similarity.  Students will learn about enlargement, scale factors, area growth indirect measurement, and other similarity-related concepts.  Similarity is an example of proportionality.  Piaget considered that proportional reasoning is one of the six abilities that characterize formal –operational thinking.

 

Enduring Understandings

·         Principles of similarity are an integral part of the world around us, especially in the areas of architecture, art and design

·         Scaling makes things bigger or smaller, but it maintains the relationship between parts

·         Geometric figures can change position and maintain the same attributes in a plane (transformations)

 

Essential Questions

·         What does twice as big mean? What are we talking about?

·         When figures are similar, how are the lengths, area and scale factors related?

·         How does the transformation of a geometric figure affect its attributes?

GLEs: 1, 4, 5, 9, 10, 11, 12, 13, 20, 21, 22, 24, 25, 27, 28, 29, 30, 39, 40, 41

 

Students will know…

·         Similarity (when two objects are identical except for proportional differences in lengths and areas.)

·         Enlargement (a copy of a given figure that is proportionately larger)

·         Image (the resulting figure when a given figure is enlarged /stretched or shrunk)

·         Correspondence (given a figure and an image of it, knowing which segments or vertices in the original figure correspond to segments or vertices in the image)

·         Transformation (changing a figure in a consistent way)

·         Transformation rule (defines how a figure is to be transformed, often given in (x,y) coordinate form)

·         Scale factor (number multiplied by the dimensions of the original figure to transform it into an image similar to the original figure)

·         Reptiles (figures made with copies of a given figure)

·         Map scales (linear scales given on maps that can be used to find distances and areas)

·         Similar triangles (triangles which have congruent corresponding angles)

·         Ratio (comparison of two quantities that gives the scale factor between them)

 

Students will be able to…

·         Enlarge and shrink plane figures (with rubber-band stretcher and scale factors)

·         Subdivide figures (to determine scale factors)

·         Use scale maps, diagrams, and figures (use scale factors to find actual distances/areas with scale maps, diagrams, and similar figures)

·         Solve problems using properties of similar triangles

·         Compute applications of similarity

·         Identify and draw angles, circles, diameters, radii, attitudes and two-dimensional figures with given specifications, including their reflections and translations on a coordinate grid

·         Locate and plot coordinates in all four quadrants (including missing vertex in a parallelogram)

·         Recognize and compute equivalent representations (fractions, decimals, and percents)

·         Compute fractions and decimals (four basic operations)

·         Compare, order, and convert measurements and area using common reference points (within and between US and metric systems)

·         Recognize that pi is the ratio between the circumference and diameter of any circle

·         Apply of circle attributes in real life problems (i.e. radius, diameter, circumference, and area)

·         Apply knowledge of triangles (measures of interior angles add up to 180°)

·         Model and explain how scale change in linear dimensions affects perimeter/circumference and area of a two dimensional figure

Assessments

·       Performance Task

·       Performance Task Rubric

·       Performance Task Key

·       Cartoon Enlargement Instructions

·       Unit Review

·       Unit Test 1

·       Unit Test 2

·       Unit Test 3

·       Unit Test 4

·       Unit Test 5

·       Unit Test 6

 

 

 

 

 

·       Inv. 1-2 Review

·       Inv. 1-2 Reflection

·       Inv. 1 & 2 Check-Up

·       Inv. 1 & 2 Retest

·       Inv. 1-3 Summary

·       Inv. 1-3 Summary Key

·       Inv. 1-3 Review

·       Inv. 1-3 Quiz

·       Inv. 1-3 Test A

·       Inv. 1-3 Test B

·       Inv. 5 Review 1

·       Inv. 5 Review 2

·       Inv. 5 Quiz

·       S & S Review 1

·       S & S Jeopardy Review

·       S & S Jeopardy Key