	What is wrong with the following program that prints all divisors?
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\begin{Verbatim}
  \textbf{def} divisors(n):
    \textbf{for} d \textbf{in} range(1, \red{n}):
      \textbf{if} n % d == 0:
        \textbf{print}(d)
\end{Verbatim}			
			\end{column}
			\begin{column}	{0.50\textwidth}
				Answer: \texttt{range(1,n)} generates values up to \texttt{n-1}, so \texttt{n} is not printed. Instead, \texttt{range(1,n+1)} is better. 
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			\end{columns}
			
				\vspace{2cm}
				Teachers can often spot such erroneous patterns without test cases. Can we represent their knowledge and use it to:
				\begin{itemize}
					\item generate automatic feedback in tutoring systems or
					\item find programs with similar approach / error?
				\end{itemize}				
				Two research questions arise: 
				\begin{itemize}
					\item RQ1: How can we encode patterns in programs? 
					\item RQ2: How can we automatically extract relevant patterns from student solutions?
				\end{itemize}