Without this, I was getting:

    uninitialized constant CreateTeamNames::Team/home/sit/src/exercism.io/lib/db/migrate/10_create_team_names.rb:4:in `up'
    /home/sit/.rbenv/versions/1.9.3-p374/lib/ruby/gems/1.9.1/gems/activerecord-3.2.15/lib/active_record/migration.rb:410:in `block (2 levels) in migrate'

Do you need something else to make it work?