Framebox - two rows

Please how to set two rows in a framebox?

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[czech,english]{babel}

\begin{document}
\framebox[\textwidth]{\centering \textbf{Instruction:}\\ Find the ground state energy of a helium atom in first-order perturbation theory.} \par
\end{document}


Is the instruction grammatically correct?

\framebox creates a single line box. Click here for more info.

Since you have many lines in your box, you could use framed environment, from the package of the same name.

Off-topic: don't use \\ for going to a new line, just leave an empty line.

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[czech,english]{babel}
\usepackage{framed}

\begin{document}
\begin{framed}\centering\textbf{Instruction:}

Find the ground state energy of a helium atom in first-order perturbation theory.
\end{framed}
\end{document}


• Thank you and how to set bold border please? I editted the code in question. – Elisabeth Nov 4 '18 at 8:03
• @Johannes_B Elisabeth asked a new question: tex.stackexchange.com/questions/458298/mdframed-bold-frame. I deleted the edit to her question. – CarLaTeX Nov 4 '18 at 8:19
• For a bold border, you have \setlength{\FrameRule}{some length}. – Bernard Nov 4 '18 at 11:55
• @Elisabeth you can have bold border also with framed: see Bernard's comment. – CarLaTeX Nov 4 '18 at 13:17