This is due to the plummeting birthrate and not due to an exodus from the government schools. From the Idaho Press:
The tail end of 2023 saw controversy surrounding the Nampa School District’s plan to close four schools by the next academic year. The decision came as a shock to many in the community, but the district has maintained that conversations had been ongoing for years, Idaho Press reporter Haadiya Tariq writes.
One factor has stood at the center of those conversations — low enrollment.
…
The 2023-2024 academic year has been the first time in a decade that public schools in Idaho have seen a statewide decrease in enrollment, not accounting for the peak of the pandemic in 2020, as first reported by IdahoEdNews. Fall of 2023 saw 1,500 fewer students than the year prior.Based on the Idaho Department of Education’s historical data, the state as a whole has lost over 29,000 students since the 2013-2014 school year.