Complex sentence: Manualists claim that oralists neglect the psychosocial development of deaf children, and that the extensive practice required leaves students with less time and energy to advance academically and socially.
Split into simpler sentences: Manualists claim that oralists neglect the psychosocial development of deaf children. In their training in articulation, which requires long tedious practice, oralism leaves students with less time and energy to advance academically and socially.