# Prevalence of Typical Images in High School Geometry Textbooks

2017

Thesis

M.A.

## Degree Name

Master of Arts (M.A.)

## Degree Granting Department

Mathematics and Statistics

## Major Professor

Milé Krajčevski, Ph.D.

## Committee Member

Catherine A. Bénéteau, Ph.D.

## Committee Member

Denisse Thompson, Ph.D.

## Keywords

Visualization, Math Education, Textbook Analysis, Concept Definition, Geometry

## Abstract

Visualization in mathematics can be discussed in many ways; it is a broad term that references physical visualization objects as well as the process in which we picture images and manipulate them in our minds. Research suggests that visualization can be a powerful tool in mathematics for intuitive understanding, providing and/or supporting proof and reasoning, and assisting in comprehension. The literature also reveals some difficulties related to the use of visualization, particularly how illustrations can mislead students if they are not comfortable seeing concepts represented in varied ways. However, despite the extensive research on the benefits and challenges of visualization there is little research into what types of figures students are exposed to through their textbooks.

This study examines 14 high school geometry textbooks in total, comprised of eight physical textbooks from the top three major textbook publishers in the United States and six FlexBooks created by a non-profit organization developing free and customizable textbooks online. In each textbook the printed images from four topics were classified: Parallel Lines and Transversals, Classifying Triangles, Parallelograms, and Trapezoids. The ‘typical’ images in each of the four topics were defined and the percentages of images that were typical for each textbook in both the lesson and exercise portions were calculated. Results indicate that lesson portions of sections generally contain more typical images than exercise portions and that the total percentage of typical images in an average section varies from 51.9% typical images in the Parallel Lines and Transversals section to 75.2% typical images in the Trapezoid section. Based on these results we list possible avenues for further research in this area.

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