  Disfluencies are prevalent in spontaneous speech, as shown in many studies of
adult speech. Less is understood about children's speech, especially in
pre-school children who are still developing their language skills. We present
a novel dataset with annotated disfluencies of spontaneous explanations from 26
children (ages 5--8), interviewed twice over a year-long period. Our
preliminary analysis reveals significant differences between children's speech
in our corpus and adult spontaneous speech from two corpora (Switchboard and
CallHome). Children have higher disfluency and filler rates, tend to use nasal
filled pauses more frequently, and on average exhibit longer reparandums than
repairs, in contrast to adult speakers. Despite the differences, an automatic
disfluency detection system trained on adult (Switchboard) speech transcripts
performs reasonably well on children's speech, achieving an F1 score that is
10\% higher than the score on an adult out-of-domain dataset (CallHome).
