\begin{frame} \frametitle{Block Structures} \begin{exampleblock}{Allowed block structures} Blocks are allowed to be nested inside each other: \begin{center} \begin{tikzpicture}[thick] \draw (0,0) rectangle (1.5cm,2cm); \end{tikzpicture} \hspace{1cm}\pause \begin{tikzpicture}[thick] \draw (0,0) rectangle (1.5cm,2cm); \draw (.3cm,.3cm) rectangle (1.2cm,1.3cm); \end{tikzpicture} \hspace{1cm}\pause \begin{tikzpicture}[thick] \draw (0,0) rectangle (1.5cm,2cm); \draw (.3cm,.3cm) rectangle (1.2cm,.8cm); \draw (.3cm,1.1cm) rectangle (1.2cm,1.7cm); \draw (.5cm,1.3cm) rectangle (1cm,1.5cm); \end{tikzpicture} \end{center} \end{exampleblock} \pause \begin{alertgoal}{} Blocks are not allowed to intersect: \begin{center} \begin{tikzpicture}[thick] \draw (0,0) rectangle (1.5cm,2cm); \begin{scope}[shift={(-.5cm,.5cm)}] \draw (0,0) rectangle (1.5cm,2cm); \end{scope} \end{tikzpicture} \hspace{1cm} \begin{tikzpicture}[thick] \draw (0,0) rectangle (.9cm,2cm); \begin{scope}[shift={(-.3cm,.5cm)}] \draw (0,0) rectangle (1.5cm,2cm); \end{scope} \end{tikzpicture} \end{center} \end{alertgoal} \end{frame}