Create fill-in-the-blank version of a document with ability to toggle blanks on and off

Question

I am preparing some lecture notes/slides and would like to efficiently create two versions of the output: a complete version for myself, and a version for my students with certain text replaced with blanks or an empty box so that they can fill it in during lectures.

the \underline{\phantom{text}} command does the trick, but it would be time consuming to create a separate version of the document and insert this in all the relevant places.

How can one use macros to give us the ability to easily toggle between the teacher version (with full text) and student version (with blanks)?

I was going to post this as a question but then figured it out so thought I'd share it.

Answer 1

The censor package will break across lines with the \blackout and \xblackout commands. The first will show inter-word spaces. The latter will not.

By default, the "blackout" is a thick \rule. To make it an underline (use Version 3.21 of censor, dated 30-JUL-13), I reset the parameters \censorruledepth and \censorruleheight.

\documentclass{article}
\usepackage{censor}
\censorruledepth=-.2ex
\censorruleheight=.1ex
%\StopCensoring
\begin{document}
An the answer is \xblackout{forty two}.

The beginning six words of the Gettysburg Address are \blackout{Four score and seven years ago}.
\end{document}

Uncommenting the \StopCensoring command will put your text back into the document, i.e., create the teacher's copy.

EDITED to reflect availability of V3.21 censor (bug fix) at at http://ctan.org/tex-archive/macros/latex/contrib/censor

Answer 2

Create a macro called \doBlank with two versions: one which replaces the argument with an underlined blank, and the other which leaves the argument unchanged. Then, to toggle between document versions we simply comment out one definition or the other:

Here is the teacher's version:

\documentclass[a4paper,12pt]{article}

%\newcommand{\doBlank}[1]{\underline{\phantom{#1}}}
\newcommand{\doBlank}[1]{#1}

\begin{document}

The last five words \doBlank{are replaced by a blank}.

\end{document}

Now for the student's version:

\documentclass[a4paper,12pt]{article}

\newcommand{\doBlank}[1]{\underline{\phantom{#1}}}
%\newcommand{\doBlank}[1]{#1}

\begin{document}

The last five words \doBlank{are replaced by a blank}.

\end{document}

Answer 3

My colleague and I have adapted this code from the eqexam package and used it for fill-in questions in examinations:

\newcommand{\fillin}[3][u]{  
%% #1= the box (u=underlined, e=empty, b=boxed) #2= space for the  
%% answer, #3= the correct answer  
\space  
    \ifx#1u\let\fillin@Fmt=\underbar%%% by default underlined space  
    \else\ifx#1e\let\fillin@Fmt=\relax%%% empty space  
    \else\ifx#1b\let\fillin@Fmt=\fbox%%% box  
    \fi\fi\fi  
     \fillin@Fmt{\parbox[b][.8\height][b]{#2}{%  
            \strut\hfil\fill@ans@color{#3}\hfil}%  
 }  
 }

We have tried to have the text of the answer splitted across lines, but it does not work. As in this command you can define the length of the blank space, the problem of the greater space to be filled by hand should be solved.

We will think about the possibility to split text across lines and we will post the solution if find it.

EDIT:

A part of the code missing in my previous answer. I apologize.

Here is a m.w.e. with the complete code:

\documentclass{article}  
\usepackage{calc} 

\newif \ifteacher  

\makeatletter  
    \ifteacher  
    \teachertrue  
    %\teacherfalse
    \def\fill@ans@color#1{\bfseries\color{red}{#1}}%%% with solutions  
    answers are in red by default  
    \else  
    \def\fill@ans@color#1{\phantom{#1}}%%% without solutions option -> no  
    answers
    \fi  

\newcommand{\fillin}[3][u]{  
%% #1= the box (u=underlined, e=empty, b=boxed) #2= space for the  
%% answer, #3= the correct answer  
\space  
    \ifx#1u\let\fillin@Fmt=\underbar%%% by default underlined space  
    \else\ifx#1e\let\fillin@Fmt=\relax%%% empty space  
    \else\ifx#1b\let\fillin@Fmt=\fbox%%% box  
    \fi\fi\fi  
    \fillin@Fmt{\parbox[b][.8\height][b]{#2}{%  
        \strut\hfil\fill@ans@color{#3}\hfil}%  
 }  
 }  
\makeatother  

\begin{document}  


2+4=\fillin{4cm}{6}  
\end{document}

If you want teacher version you have to uncomment the \teachertrue command, if you want student version you have to uncomment the other one.

EDIT 2

The switch \teachertrue or \teacherfalse must be put in the preamble. The above code should now work.

Answer 4

Answering a question on fr.comp.text.tex (see end of the discussion), Paul Isambert wrote some code using LuaTeX machinery (code links are now broken). At the time, we discussed that matter privately by email and Paul enhanced his code to fit my needs. He gave me the permission to post the resulting code (PAT = 'poly à trous', code commented in French, feel free to fork and/or commit).

From my point of view, one thing that is really interesting is that it avoids "orphan" blanks at the beginning of a line: if the blank at the beginning of a line is too small, then it is discarded. It is also robust enough to go through maths, texts and mixture of both.

It is a good example of how attributes can be used to do some "post processing" with LuaTeX.

\documentclass{article}

\usepackage{PAT,pgffor}

\def\test#1{%
  \foreach \i in {1,...,#1}{%
    test }}

\begin{document}

Test \trou{Test} Test

Test \trou{\test{20}} Test

Test \trou{$\displaystyle\int$ Test} Test

Test $\displaystyle \trou{\int_{0}^{t^2} x^2 dx}$ Test

Test $$\int_{0}^{\trou{t^{2}}} \frac{x^2}{\trou{2}} dx$$ Test

Test \trou{abc \par def} Test

\end{document}