\begin{frame}
  \frametitle{Key Quiz}
  
  \centering
  \begin{quiz}{1\textwidth}{Keys for an appointment calendar}
    \raggedright
    \centerline{%
      \ttfamily\small
      \colorbox{rellight}{%
        \begin{tabular}[t]{|r|r|r|r|r|}
          \multicolumn{5}{c}{Appointments}        \\ \hline
          \hd{date} & \hd{start} & \hd{end} & \hd{room} & \hd{event}\\ \hline
          Jan. 19 & 10:00 & 11:00 & WN 726 & Seminar  \\
          Jan. 19 & 14:00 & 16:00 & WN 726 & Lecture  \\
          May\ \ \ 24 & 14:00 & 18:00 & Amsterdam & Meeting  \\
          \hline
        \end{tabular}%
      }
    }
  
  \bigskip
  
  \begin{itemize}
  \item What would be correct minimal keys for this database?
  \item What would be an example for a superkey?
  \item Are additional constraints useful to exclude database states
    that a key would still permit?
  \end{itemize}
  \end{quiz}
\end{frame}

% \overview{5}
\theme{Foreign Keys}