  The increasing use of interactive learning strategies in Astro 101 classrooms
has led some instructors to consider the usefulness of a textbook in such
classes. These strategies provide students a learning modality very different
from the traditional lecture supplemented by reading a textbook and homework,
and raises the question of whether the learning that takes place during such
interactive activities is enough by itself to teach students what we wish them
to know about astronomy. To address this question, assessment data is presented
from an interactive class, which was first taught with a required textbook, and
then with the textbook being optional. Comparison of test scores before and
after this change shows no statistical difference in student achievement
whether a textbook is required or not. In addition, comparison of test scores
of students who purchased the textbook to those who did not, after the textbook
became optional, also show no statistical difference between the two groups.
The Light and Spectroscopy Concept Inventory (LSCI), a research-validated
assessment tool, was given pre- and post-instruction to three classes that had
a required textbook, and one for which the textbook was optional, and the
results demonstrate that the student learning gains on this central topic were
statistically indistinguishable between the two groups. Finally, the Star
Properties Concept Inventory (SPCI), another research-validated assessment
tool, was administered to a class for which the textbook was optional, and the
class performance was higher than that of a group of classes in a national
study.
