<div class="field">
  <br /><%= f.label "Challenges" %><br />
  <% for challenge in Challenge.all %>
    <%= check_box_tag 'badge[challenge_ids][]', challenge.id, @badge.challenge_ids.include?(challenge.id), :id => dom_id(challenge) %>
    <%= label_tag dom_id(challenge), challenge.title, :class => "check_box_label" %>
  <% end %>
</div>