old_contents: from django.contrib import admin
  from django.utils.html import format_html
  
  from planner.models import School, Student
  
  
  @admin.register(School)
  class SchoolAdmin(admin.ModelAdmin):
      def clickable_url(obj):
          return format_html(
              '<a href="{0}" target="_blank">{1}</a>', obj.url, obj.url)
      clickable_url.short_description = 'url'
  
      list_display = ('name', clickable_url, 'milestones_url')
      list_per_page = 10
      ordering = ['id']
      search_fields = ['name']
  
  
  @admin.register(Student)
  class StudentAdmin(admin.ModelAdmin):
      list_display = ('last_name', 'first_name', 'class_year')
  
new_contents: from django.contrib import admin
  from django.utils.html import format_html
  
  from planner.models import School, Semester, Student
  
  
  @admin.register(School)
  class SchoolAdmin(admin.ModelAdmin):
      def clickable_url(obj):
          return format_html(
              '<a href="{0}" target="_blank">{1}</a>', obj.url, obj.url)
      clickable_url.short_description = 'url'
  
      list_display = ('name', clickable_url, 'milestones_url')
      list_per_page = 10
      ordering = ['id']
      search_fields = ['name']
  
  
  @admin.register(Semester)
  class SemesterAdmin(admin.ModelAdmin):
      list_display = ('date', 'active')
  
  
  @admin.register(Student)
  class StudentAdmin(admin.ModelAdmin):
      list_display = ('last_name', 'first_name', 'class_year')
  
subject: Add Semester admin.