app/views/invitations/new.html.erb
<h1>New Invitation</h1>
<%= form_for @invitation do |f| %>
<%= f.label :email, "Emails" %>
<%= f.text_area :email, placeholder: "Comma separated list of email addresses" %>
<%= select_tag :role, options_for_select(["mentor", "invited"]), id: "role-select" %>
<%= label_tag :role %>
<%= f.submit "Invite" %>
<% end %>