\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}

\begin{tikzpicture}
  \draw (0,0) -- (8, 0) -- (8, 6) -- (0, 6) -- cycle;
  \draw [dashed] (2,0) -- (2, 6);
  \draw [dashed] (0,4) -- (8, 4);
  \draw (1, 2) node[anchor=north] {$A_1$};
  \draw (1, 5) node[anchor=north] {$A_2$};
  \draw (5, 2) node[anchor=north] {$A_3$};
  \draw (5, 5) node[anchor=north] {$A_4$};
\end{tikzpicture}

\end{document}