Teacher's Guide

This unit was designed for middle school students who have had no prior experience with fractal geometry. It should lead them through the definition of a fractal, multiple examples of fractals, where fractals can be found, and how to compose a simple fractal from scratch. It can be used as an individual tutorial, or as the basis for classroom lessons. When used for classroom lessons, the unit provides opportunities for individual work, pair inquiry, as well as group research. Here I will outline how the unit addresses the NCTM Standards, activities that provide opportunities for student assessment, and relevant references and links that can be explored.

NCTM Standards Addressed

What are Fractals?

#2 Mathematics as communication: develop common understandings of mathematical ideas, including the role of definitions.

#8 Patterns & functions: describe, extend, analyze, and create a wide variety of patterns.

#12 Geometry: identify, describe, compare, and classify geometric figures.

Fractals in Nature

#1 Mathematics as problem solving: generalize solutions and strategies to new problem situations.

#2 Mathematics as communication: use the skills of reading, listening, and viewing to interpret and evaluate mathematical ideas.

#3 Mathematics as reasoning: recognize and apply deductive and inductive reasoning.

#4 Mathematical connections: see mathematics as an integrated whole.

#8 Patterns and functions: describe, extend, analyze, and create a variety of patterns.

#12 Geometry: develop an appreciation of geometry as a means of describing the physical world.

Properties of Fractals

#1 Problem solving: use problem-solving approaches to investigate and understand mathematical content.

#2 Mathematics as communication: develop common understandings of mathematical ideas, including the role of definitions.

#3 Mathematics as reasoning: make and evaluate mathematical conjectures and arguments.

#4 Mathematical connections: use a mathematical idea to further their understanding of other mathematical ideas.

#8 Patterns and functions: describe and represent relationships with tables, graphs, and rules.

#9 Algebra: analyze tables and graphs to identify properties and relationships.

#10 Statistics: make inferences and convincing arguments that are based on data analysis.

#12 Geometry: explore transformations of geometric figures.

Creating a Fractal

#2 Mathematics as communication: reflect on and clarify their own thinking about mathematical ideas and situations.

#3 Mathematics as reasoning: validate their own thinking.

#5 Number and number relationships: understand and apply ratios, proportions, and percents in a wide variety of situations.

#8 Patterns and functions: describe, extend, analyze, and create a wide variety of patterns.

#12 Geometry:
visualize and represent geometric figures with special attention to developing spatial sense;
understand and apply geometric properties and relationships;
explore transformations of geometric figures.

Student Assessment

There are several activities throughout the unit that lend themselves to formal student assessment. They include:

  • pages produced as a result of the Fractal Scavenger Hunt;
    -does the image found fit the definition of a fractal?
    -check if the seed is accurately identified
    -confirm the number of iterations noted by the group
    -was the source of the fractal appropriately identified?
  • table and worksheet questions from the Coastline Simulation;
    -accuracy of completing the table and computing the distances
    -validity of conjectures made in regard to the Koch Snowflake perimeter
  • table and worksheet questions from the Sierpinski Triangle activity;
    -accuracy of completing the table and computing the areas
    -validity of conjectures made in regard to the Sierpinski Triangle area
  • the end of the unit fractal each student creates individually.
    -is there a visible seed for the fractal?
    -does each iteration follow the same pattern in the same proportions?

    Informal assessment can be made by observations of how students work in cooperative pairs and groups, how proficient they become using web browsers, and how they communicate ideas verbally to their peers.

    I believe that each teacher needs to decide for themselves which activities will carry the most weight or what additional activities are necessary to conclude assessment to decide grades for the unit. Each class may have distinct goals or areas of focus. I feel the end of the unit fractal lesson is a strong alternative to a test to see if students have assimilated the main ideas of the unit.

    References & Links

  • a great resource book for photos of natural fractals and explanations of fractals is:
    McGuire, Michael. An Eye For Fractals, Addison-Wesley Publishing Company, Redwood City, CA, 1991

  • for lots of questions and answers about fractals, try sci.fractals FAQ at: http://www.mta.ca/~mctaylor/sci.fractals-faq/toc.html

  • the animated Koch Curve in "What are Fractals" can be found at Free Cloud's Fractal Land

  • a biography about Benoit Mandelbrot can be found at: http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Mandelbrot.html

  • the examples of fractal music were composed by Martin Guertner and come from the Fractal Music Project at: http://www-ks.rus.uni-stuttgart.de/people/schulz/fmusic/

  • a good page to zoom in on fractals and see the continuing patterns is the Fractal Explorer at:
    http://www.vis.colostate.edu/cgi-bin/fractals/imagemap/imagemap/idx?204,41

  • the sample fractal link in "What are Fractals?" is NASA Fractals at: http://www.lerc.nasa.gov/Other_Groups/K-12/fracpage.html

  • an assortment of examples for "Fractals in Nature" can be found at Fractal Images of CNAM Paris under Ifs Pictures at: http://www.cnam.fr/fractals/ifs.html

  • the Fractal Coastline software used in "Properties of Fractals" can be found at: http://cps-www.bu.edu/~trunfio/ogaf-programs.html

  • the triangular grid paper used for the Sierpinski Triangle comes courtesy of Cynthia Lanius at http://cml.rice.edu/~lanius/images/triangle.gif

  • the arrow & letter examples of fractals used in "Creating a Fractal" can be found at the Fractal Icon Archive at: http://www.dd.chalmers.se/~gu94joli/icons.html

  • a great overall link for fractals is the Spanky Fractal Database at: http://spanky.triumf.ca/

  • finally, some sites that just have beautiful fractal examples to explore include:
    Glimpses of a Fugitive Universe, The Recursive Art of Rollo Silver at: http://www.artvark.com/artvark/index/index.html
    Tim Michaelson's FRACTAL ART GALLERY at: http://www.top.net/tim/fractal/fractal.htm
    Eric's Fractal Gallery at: http://snt.student.utwente.nl/~schol/gallery--be sure to go into Room II and see the large version of Bluedive

    Return to Table of Contents.

    Please send me any comments or suggestions you have about the unit.