Rule reminder
Direct: mi/ti/lo/la/ci/vi/li/le (replaces who/what). Indirect: mi/ti/gli/le/ci/vi/gli (replaces to whom). For 3rd person: lo/la/li/le (direct) vs. gli/le (indirect).
Sento i bambini che giocano. → _____ sento. (replacing 'i bambini' as direct object)