\documentclass{article}
\usepackage{latex-macros/course}

\begin{document}
This is standard text This is standard text This is standard text This is standard text 
This is standard text This is standard text This is standard text This is standard text 
This is standard text This is standard text This is standard text This is standard text 
This is standard text This is standard text This is standard text This is standard text 
This is standard text This is standard text This is standard text This is standard text 
\begin{optional}
and this is some optional piece
and this is some optional piece
and this is some optional piece
and this is some optional piece
and this is some optional piece
and this is some optional piece
and this is some optional piece
and this is some optional piece
\end{optional}
This is standard text This is standard text This is standard text This is standard text 
This is standard text This is standard text This is standard text This is standard text 
This is standard text This is standard text This is standard text This is standard text 
This is standard text This is standard text This is standard text This is standard text 
This is standard text This is standard text This is standard text This is standard text 
This is standard text This is standard text This is standard text This is standard text 

\end{document}	