class ParticipatingSchoolsController < ApplicationController
  def index
    @schools = School
      .participating
      .includes(town: {municipality: :state})
      .order('town_id, name')
  end

  def show
    @school = School.participating.find(params[:id])
  end
end

class ParticipatingSchoolsController < ApplicationController
  def index
    @schools = School.participating.with_location_info.order('town_id, name')
  end

  def show
    @school = School.participating.find(params[:id])
  end
end

Use the new School.with_location_info scope
Use the new School.with_location_info scope