  The lengthy monologue-style online lectures cause learners to lose engagement
easily. Designing lectures in a "vicarious dialogue" format can foster
learners' cognitive activities more than monologue-style. However, designing
online lectures in a dialogue style catered to the diverse needs of learners is
laborious for instructors. We conducted a design workshop with eight
educational experts and seven instructors to present key guidelines and the
potential use of large language models (LLM) to transform a monologue lecture
script into pedagogically meaningful dialogue. Applying these design
guidelines, we created VIVID which allows instructors to collaborate with LLMs
to design, evaluate, and modify pedagogical dialogues. In a within-subjects
study with instructors (N=12), we show that VIVID helped instructors select and
revise dialogues efficiently, thereby supporting the authoring of quality
dialogues. Our findings demonstrate the potential of LLMs to assist instructors
with creating high-quality educational dialogues across various learning
stages.
