1. Rebecca S. Burton Department of Biology Alverno College Milwaukee, WI
Readability, Logodiversity, and the Effectiveness of College Biology Textbooks
Rebecca S. Burton   Department of Biology
Alverno College
Milwaukee, WI

2. Context
Only 38% of students nearing graduation from 4-year colleges are proficient enough in prose literacy to understand materials such as textbooks
Students we most want to recruit to STEM fields might have less prose literacy
Student text literacy does not increase with number of years in college
(Baer, et al The Literacy of America’s College Students)

3. Questions
Does the amount of technical vocabulary (logodiversity) influence student comprehension of college biology textbooks?
Does the grade level of prose (readability) influence student comprehension of college biology textbooks?
Are students reading their college biology textbooks?
If so, is it improving their comprehension of concepts?

4. Methods: Readings Biology: Concepts & Connections
Campbell et al., 5th Edition.
Original version
Low Logodiversity version
Low Grade Level version—as measured by 3 common indices.
All in same font and format and without figures

5. The Flesch–Kincaid Grade Level (FKGL)
The Coleman-Liau Index (CLI)
0.0588L – 0.296S – 15.8
Where:
L is the average number of letters per 100 words and
S is the average number of sentences per 100 words. 
The Automated Readability Index (ARI)

6. Readability: Grade Level Scores
Freshman college students are assumed to be able to comprehend readings at grade level 13.

7. Methods: Subjects
Students in 3 of 6 sections of introductory biology for majors (approximately 60)
Female
College-wide (no demographic data available for sample):
58 % Caucasian American
17 % African American
14 % were Hispanic American
5 % Asian American
4 % Non-US residents or multiple ethnicities.
College-wide, 88% of full-time undergraduates on financial aid

8. Methods: Procedure Usual pre-class reading assignment (Krogh)
In Class:
Randomly given 1 of 3 versions of reading
Set of questions (same for all)
IF-AT answer card

9. 2. Version of in-class reading? 3. Did the pre-class reading?
This section removed
1. Consent?
2. Version of in-class reading?
3. Did the pre-class reading?
4-9. Content questions
Correct on 1st try = 5, Correct on 2nd try = 3, Correct on third try = 1

10. Questions Vocabulary Factual recall Summary Application Extension
Control: In pre-class reading, but not in-class reading
“Total” does not include the control question

11. Statistical Analysis
Did version (original, low logodiversity, or low grade level index) influence student performance?
ANOVA
Did students who reported completing the pre-class reading outperform those who reported that they had not or were not sure?
One-tailed, independent T-tests

12. Population Ecology Sample size = 19, 19, and 18. ANOVA, P = 0.8

13. Enzymes Sample size = 17, 17, and 18. ANOVA, P = 0.03

14. Photosynthesis Sample size = 14, 14, and 15. ANOVA, P = 0.88

15. Inheritance Sample size = 14, 16, and 17. ANOVA, P = 0.067

16. Reading and Performance

17. Question Type
Type of Question and Performance

18. Summary of Results
Lower logodiversity and grade level increased comprehension for the most difficult topic.
Compliance with reading assignments was low and declined steeply.
Reading the textbook before class did not significantly improve performance.
Comprehension of the in-class reading was fairly low for some topics.

19. Speculation
When a concept is fairly easy to grasp, decreasing logodiversity or reading level is not necessary.
The readability improvement may not have been enough to improve comprehension of some concepts.
Increasing readability may not be sufficient without accompanying visual representations.
Students are using textbooks differently than most instructors expect.

20. Additional Questions
Will simultaneously decreasing logodiversity and grade level readability improve students’ comprehension of the reading?
Will greater decreases in grade level readability improve students’ comprehension of the reading?
Will adding figures improve performance?
What interventions increase reading compliance and comprehension?

21. Implications for Teaching
Selecting a textbook with lower logodiversity (ratio of glossary to text) and grade level index may improve student reading comprehension.
Students may need external motivation to increase reading compliance.
Students may need assistance to make their reading an effective learning tool.

22. Thanks! Amal El-Sheikh, collaborator Paul Smith, Alverno IRB
Dawn Balistreri, editor