\documentclass[a4paper]{article}

% Packages
\usepackage[a4paper, inner=2.5cm, outer=2.5cm, top=2.5cm, bottom=2cm, bindingoffset=0cm]{geometry}
\usepackage{amsmath,amsthm,amssymb,amsfonts}
\usepackage{graphicx}
\usepackage[colorlinks=true, allcolors=blue]{hyperref}
\usepackage{fontspec,xunicode,xltxtra}

% GERMAN
\usepackage[ngerman=ngerman-x-latest]{hyphsubst}
\usepackage[ngerman]{babel}

% Figures
\graphicspath{{figures/}}

\begin{document}

\title{ABI Zeitung 2021}
\author{des RBS Ulm}

% Updated: https://tex.stackexchange.com/a/7657
% Import all tex files from a directory
\def\app@exe{\immediate\write18}
\def\Ainput#1{
    \app@exe{cat #1/*.tex > #1/files.tmp}
    \InputIfFileExists{#1/files.tmp}{}{}
    \AtEndDocument{\app@exe{rm -f #1/files.tmp}}}

\maketitle

%\tableofcontents

\section{Einführung}
Heeerzlich willkommen!

\Ainput{parts/students/}

\end{document}