Presentation using beamer

Question

Using beamer I have prepared the following slide. I want to display the theorem in a box or like that for better presentation. Also title heading is left align. Is it ok or not?

\begin{frame}{Chinese Remainder Theorem(CRT)}

\begin{theorem}

 Let $r, s$ be integers such that gcd$(r, s)=1$. 
Given integers $a,b$, there exists unique 
$x <rs$ such that 

\vspace*{5pt}
\begin{enumerate}
\item $x \equiv a \bmod r$ 
\item $x \equiv b \bmod s$
\end{enumerate}

\end{theorem} 

\end{frame}

Answer 1

Do you mean something like this?

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usetheme{Madrid}
\title{You slide ready}
\author{Yourself}
\date{today}

\begin{document}
\begin{frame}[shrink=-50]{A theorem in a box}

\begin{theorem}

 Let $r, s$ be integers such that gcd$(r, s)=1$. 
Given integers $a,b$, there exists unique 
$x <rs$ such that 

\begin{enumerate}
\item <+-> Wait to the next slide ...
\item <+-> $x \equiv a \bmod r$ 
\item <+-> $x \equiv b \bmod s$
\end{enumerate}

\end{theorem} 
\end{frame} 
\end{document}

Well, without theme and without theorem environment, you can use, for example, fancybox and minipage:

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage{fancybox}
\title{You slide ready}
\author{Yourself}
\date{today}
\begin{document}
\begin{frame}[shrink=-50]{A theorem in a box}

 Let $r, s$ be integers such that gcd$(r, s)=1$. 
Given integers $a,b$, there exists unique 
$x <rs$ such that 

\Ovalbox{\begin{minipage}[t]{0.5\columnwidth}%

\begin{enumerate}
\item <+-> Wait to the next slide ...
\item <+-> $x \equiv a \bmod r$ 
\item <+-> $x \equiv b \bmod s$
\end{enumerate}

\end{minipage}}
\end{frame} 
\end{document}