  We report on our ongoing efforts to develop, implement, and test VR
activities for the introductory astronomy course and laboratory. Specifically,
we developed immersive activities for two challenging "3D" concepts: Moon
phases, and stellar parallax. For Moon phases, we built a simulation on the
Universe Sandbox platform and developed a set of activities that included
flying to different locations/viewpoints and moving the Moon by hand. This
allowed the students to create and experience the phases and the eclipses from
different vantage points, including seeing the phases of the Earth from the
Moon. We tested the efficacy of these activities on a large cohort (N=116) of
general education astronomy students, drawing on our experience with a previous
VR Moon phase exercise (Blanco (2019)). We were able to determine that VRbased
techniques perform comparably well against other teaching methods. We also
worked with the studentrun VR Club at San Diego State University, using the
Unity software engine to create a simulated space environment, where students
could kinesthetically explore stellar parallax - both by moving themselves and
by measuring parallactic motion while traveling in an orbit. The students then
derived a quantitative distance estimate using the parallax angle they measured
while in the virtual environment. Future plans include an immersive VR activity
to demonstrate the Hubble expansion and measure the age of the Universe. These
serve as examples of how one develops VR activities from the ground up, with
associated pitfalls and tradeoffs.
