mastery of data standardization, graphing, and interpretation
skills. We directly measured student learning gains by comparing
the mean scores on questions presented to students on the pre-assessment to the mean scores on matched questions (see Appendix B) presented on a midterm and a final exam (Table 1).
We also assessed affective outcomes, another key indicator of the
efficacy of our reforms. Students’ overall attitude toward the lab was
measured with campus-wide course evaluations (Appendix C)
administered at the end of the semester. To measure students’
self-perception of learning, we administered customized Student
Assessment of Learning Gains (SALG) surveys (Appendix A) to the
control (2012) and treatment (2013–16) groups (Figure 1). Finally,
we used focus group interviews at the end of the first two treatment
years (2013 and 2014) to solicit specific suggestions for improvement
from students (Table 2).
Significant Learning Gains Realized
By comparing responses to identical questions on pre- and post-assessments (midterm and final exam), we directly measured
Table 1. Student learning gains as measured by comparing performance on pretests and posttests in
2013–2014. Pretests were administered at the beginning of the semester, before students had been
exposed to the lab activities. Posttests were conducted at midterm and during the final lab. Normalized
gain (ḡ ) was calculated by averaging individual gains (Bao, 2006). See Appendix B for question details.
Pa ḡ Pretest Posttest
59.0% 87.0% 0.000b 77.0%
Simple dilutions 14.7% 68.3% 0.000b 64.3%
Serial dilutions 3.3% 64.7% 0.000b 70.1%
Using a standard
26.3% 77.8% 0.000b 36.7%
2.0% 85.0% 0.000c 85.5%
Test total 19.9% 72.7% 0.000d 70.6%
aα = 0.05 adjusted with a Bonferroni correction.
b Wilcoxon signed-rank test.
Table 2. Feedback from student focus groups. Interviews were conducted in one section of the course by
a non-biology member of the faculty with expertise in student assessment. After compiling a larger set of
responses to each question, each class voted on three that best reflected their consensus.
Focus Group Questions
Top Three Responses
What aspects of the lab helped you
• Instructor and TA were helpful during
• Learning in a hands-on way
• Practiced procedures before we had
to use them
• Learning practical techniques
• Lab manual clarity
• Group work
What aspects of the lab hindered your
• Class was too much work,
• Provide more explanation concerning
• Instructor feedback was inconsistent
• Lab write-ups were too lengthy
• Lab went over scheduled time
• Uncertainty as to why a procedure
would be done
What specific suggestions do you have
for modifying the lab?
• More class discussion
• Better preparation for the midterm
• Recap of last week’s lab every week
• Increased clarity in expectations
• Increased clarity in lab manual
• Connect lab to lecture