gistfile1.txt

binary_sensor:
  - platform: template
    sensors:
      is_school_day_today:
        entity_id:
          - calendar.is_school_day1
          - calendar.is_school_day2
          - calendar.is_school_day3
          - calendar.is_school_day4
          - calendar.is_school_day5
          - calendar.is_school_day6
        value_template: >-
          {% if is_state("calendar.is_school_day1", "on") or
             is_state("calendar.is_school_day2", "on") or
             is_state("calendar.is_school_day3", "on") or
             is_state("calendar.is_school_day4", "on") or
             is_state("calendar.is_school_day5", "on") or
             is_state("calendar.is_school_day6", "on")
          -%}
            on
          {%- else -%}
            off
          {%- endif %}