  Virtual Reality (VR) has repeatedly proven its effectiveness in student
learning. However, despite its benefits, the student equipped with a personal
headset remains isolated from the real world while immersed in a virtual space
and the classic student-teacher model of learning is difficult to transpose in
such a situation. This study aims to bring the teacher back into the learning
process when students use a VR headset. We describe the benefits of using a
companion for educational purposes, taking as a test case the concept of
gravity. We present an experimental setup designed to compare three different
teaching contexts: with a physically present real teacher, using a live video
of the teacher, and with a VR avatar of the teacher. We designed and evaluated
three scenarios to teach the concept of gravity: an introduction to the concept
of free fall, a parabolic trajectory workshop and a final exercise combining
both approaches. Due to sanitary conditions, only pre-tests are reported. The
results showed that the effectiveness of using the VR simulations for learning
and the self-confidence level of the students increased as well. The interviews
show that the students ranked the teaching modes in this order: VR companion
mode, video communication and real teacher.
