This paper investigates the role of interaction and communication kinesics in human-robot interaction. This study is part of a novel research project on sign language (SL) tutoring through interaction games with humanoid robots. The main goal is to motivate the children with communication problems to understand and imitate the signs implemented by the robot using basic upper torso gestures and sound. We present an empirical and exploratory study investigating the effect of basic nonverbal gestures consisting of hand movements, body and face gestures expressed by a humanoid robot, and having comprehended the word, the participants will give relevant feedback in SL. This way the participant is both a passive observer and an active imitator throughout the learning process in different phases of the game. A five-fingered R3 robot platform and a three-fingered Nao H-25 robot are employed within the games. Vision-, sound-, touch-and motion-based cues are used for multimodal communication between the robot, child and therapist/parent within the study. This paper presents the preliminary results of the proposed game tested with adult participants. The aim is to evaluate the SL learning ability of participants from a robot, and compare different robot platforms within this setup.