Programming new skills on a robot should take minimal time and effort. One approach to achieve this goal is to allow the robot to ask questions. This idea, called active learning, has recently caught a lot of attention in the robotics community. However, it has not been explored from a human-robot interaction perspective. We identify three types of questions (label, demonstration, and feature queries) and discuss how a robot can use these while learning new skills. Then, we present an experiment on human question-asking which characterizes the extent to which humans use these question types. Finally, we evaluate the three types of question within a human-robot teaching interaction. We investigate the ease with which different types of questions are answered and whether or not there is a general preference of one type of question over another. Based on our findings from both experiments, we provide guidelines for designing question-asking behaviors for a robot learner.
