\documentclass{beamer}
\usepackage[utf8]{inputenc}
\usetheme{Warsaw}
\usepackage{fontspec}
\setmainfont{Times New Roman}
\setsansfont{Times New Roman}
\usepackage{polyglossia}
\usepackage{amsmath,amsthm,amssymb}
\usepackage{unicode-math}
\usepackage{ragged2e} %justifying
\usepackage{tabularx}
\setbeamercolor{block body}{bg=blue!5,fg=black}
\setbeamercolor{block title}{bg=blue!40,fg=white}
\title{My first beamer page}
\author{Theofanis Ioannou}
\institute[UOI]{University of Ioannina}
\date{15-12-2025}
\begin{document}
%1
%----------------------------------------S1
\begin{frame}
\maketitle
\end{frame}
%TOC
%-----------------------------------------S2
\begin{frame}
\tableofcontents
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Εισαγωγη}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%3 \small \scriptsize \tiny
%-------------------------------------------S3
\begin{frame}{\scriptsize Η εισαγωγη μου}
\tiny
	Αυτο ειναι ενα εισαγωγικο κειμενο...
\begin{itemize}
\item[-] Περιπτωση 1
\item[$\bullet$] Περιπτωση 2
\end{itemize}
\begin{block}{Τιτλος block} 
Αυτο ειναι το πρωτο μου block
\end{block}
\end{frame}
%------------------------------------------S4
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Μεθοδολογια}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}{Μεθοδολογια της ερευνας}
%\justifying
	\begin{center}
	Πινακας Πληροφοριων
	\end{center}
	\begin{table}
		%\caption{\tinyΠινακας Πληροφοριων}\label{tab1}
		\centering
		\label{tab1}
		\begin{tabular}{|p{1.0cm}|p{2cm}|p{3cm}|}
		\hline
			\textbf{Header1} & \textbf{Header 2} & \textbf{H3}\\
		\hline
			Κειμενο...& κειμενο & κειμενο...\\
		\hline
		\end{tabular}
	\end{table}
	
\end{frame}
%------------------------------------------S5
\begin{frame}{Overlays}
	\begin{enumerate}
		\item<1>  Περιπτωση...
		\item<2>  Υποθεση...
		\item<3>  Λυση...
	\end{enumerate}
	\only<4>{\centering
		 \vspace{-3.0cm}
		 \includegraphics[width=0.5\linewidth]{tux.png}}
\end{frame}
%-----------------------------------------S5
\begin{frame}{Στηλες}
	\begin{columns}
		\column{0.6\textwidth}
		\begin{itemize}
			\item<1> O Tux
			\item<2> O Batman
		\end{itemize}
		\column{0.4\textwidth}
		\only<1>{\includegraphics[scale=0.4]{tux.png}}
		\only<2>{\includegraphics[scale=0.4]{batman.png}}
	\end{columns}
		
\end{frame}
%--------------------------------------S6
\begin{frame}
	\[
		ET_o=\frac{0.4\Delta(R_n-G)}{\sqrt{\gamma \cdot \frac{3}{4}}}
	\]

\end{frame}
\end{document}