%% 
%%  Example 01-12-1 
%%  Copyright (C) 2017 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{304.62788pt}

%StartShownPreambleCommands
\makeatletter
\newenvironment{smallequation}[1]
  {\skip@=\baselineskip#1\baselineskip=\skip@\equation}
  {\endequation \ignorespacesafterend}
\makeatother
%StopShownPreambleCommands
\begin{document}
Normal size
\begin{smallequation}{\tiny} \int_1^2\,\frac{1}{x^2}\,\mathrm{d}x=0.5 \end{smallequation}
\end{document}
