Before the 1970s, deaf people in Nicaragua were largely isolated, communicating with hearing family members through improvised home signs that had no grammar and no consistency from one household to the next. When a special education center opened in Managua in 1977, followed by a vocational school in 1980, hundreds of deaf children were brought together for the first time. The official plan to teach them spoken Spanish and lip-reading failed, but on the playground and the school buses the children began merging their home signs into something new.

This episode follows how that first-stage system, LSN, was transformed by younger students into the grammatically complex ISN, and how MIT linguist Judy Kegl arrived in 1986 to document it. We explore the mechanics the children built, from the ABA pattern for describing motion to spatial modulation, and the research of Ann Senghas and Marie Coppola showing younger cohorts standardizing grammar. We also cover the nativist versus cultural learning debate, the ethical controversy over withholding ASL, and the community’s move to writing ISN with SignWriting.

• Why home signs and ideoglossia are not the same as a language
• How rolling down became two separate grammatical units instead of one gesture
• Rotated versus unrotated space and what it revealed about generational change
• Chomsky-style hardwired grammar versus Tomasello’s joint intentional frames
• The linguistic imperialism argument and Felicia Ackerman’s critique of the research approach