  A dialogue is successful when there is alignment between the speakers, at
different linguistic levels. In this work, we consider the dialogue occurring
between interlocutors engaged in a collaborative learning task, and explore how
performance and learning (i.e. task success) relate to dialogue alignment
processes. The main contribution of this work is to propose new measures to
automatically study alignment, to consider completely spontaneous spoken
dialogues among children in the context of a collaborative learning activity.
Our measures of alignment consider the children's use of expressions that are
related to the task at hand, their follow-up actions of these expressions, and
how it links to task success. Focusing on expressions related to the task gives
us insight into the way children use (potentially unfamiliar) terminology
related to the task. A first finding of this work is the discovery that the
measures we propose can capture elements of lexical alignment in such a
context. Through these measures, we find that teams with bad performance often
aligned too late in the dialogue to achieve task success, and that they were
late to follow up each other's instructions with actions. We also found that
while interlocutors do not exhibit hesitation phenomena (which we measure by
looking at fillers) in introducing expressions pertaining to the task, they do
exhibit hesitation before accepting the expression, in the role of
clarification. Lastly, we show that information management markers (measured by
the discourse marker 'oh') occur in the general vicinity of the follow up
actions from (automatically) inferred instructions. However, good performers
tend to have this marker closer to these actions. Our measures still reflect
some fine-grained aspects of learning in the dialogue, even if we cannot
conclude that overall they are linked to the final measure of learning.
