Good listeners generally produce back-channel feedback, that is, short utterances such as "uh-huh" which signal active listening. As the rules governing back-channeling vary from language to language, second-language learners may need help acquiring this skill. This paper is an initial exploration of how to provide this. It presents a training sequence which enables learners to acquire a basic Arabic back-channel skill, namely, that of producing feedback immediately after the speaker produces a syllable or two with a sharply falling pitch. This training sequence includes an explanation, audio examples, the use of visual signals to highlight occurrences of this pitch downslope, auditory and visual feedback on learners' attempts to produce the cue themselves, and feedback on the learners' performance as they play the role of an attentive listener in response to one side of a pre-recorded dialog. Experiments show that this enables learners to better approximate proper Arabic back-channeling behavior. (Contains 5 figures and 1 table.) [This work was supported in part by the Defense Advanced Research Projects Agency.]