** Using WeBWorK **

It looks like you are seeing how the table does not wrap at all, not that it wraps in a bad way. This is just how LaTeX tabulars work, usually. But you could make those title cells be "paragraph cells" with specified widths. I'll do that in the example pasted below.

Note that PGML.pl loads niceTables.pl, so you need not load niceTables.pl explicitly.

Also there is PGML markup for tables, which I will demonstrate.

Lastly, even constraining the widths on the header cells, you are using a two-column hardcopy theme. So there is just a limit on how much width you have to work with. It may end up that if you take the widest word from each header cell, there's just not enough space.

DOCUMENT();

loadMacros('PGstandard.pl','PGML.pl','PGcourse.pl');

BEGIN_PGML
Complete the below table.

[#
    [.Approx. sample volume.]{halign => '|p{0.16}|'}
    [.Exact volume of ethanol sample (mL).]{halign => 'p{0.16}|'}
    [.Mass of grad. cylinder & ethanol sample (g).]{halign => 'p{0.16}|'}
    [.Mass of ethanol sample (g).]{halign => 'p{0.16}|'}
    [.Density of ethanol (g/mL).]*{headerrow => 1, halign => 'p{0.16}|'}

    [.[`2`].]
    [.[_]{$ans}.]
    [.[_]{$ans}.]
    [.[_]{$ans}.]
    [.[_]{$ans}.]*

    [.[`4`].]
    [.[_]{$ans}.]
    [.[_]{$ans}.]
    [.[_]{$ans}.]
    [.[_]{$ans}.]*

    [.[`6`].]
    [.[_]{$ans}.]
    [.[_]{$ans}.]
    [.[_]{$ans}.]
    [.[_]{$ans}.]*

    [.[`8`].]
    [.[_]{$ans}.]
    [.[_]{$ans}.]
    [.[_]{$ans}.]
    [.[_]{$ans}.]

#]{align => '|*{5}{c|}', horizontalrules => 1, booktabs => 0}

END_PGML

ENDDOCUMENT();