Em dashes (—) are used in written text to indicate an interpolation that is "stronger" than those indicated by parentheses and, according to some style guides, a closed range of values that spans, say, multiple chapters in one biblical book (e.g., John 1:1—3:16). En dashes (–) are used in written text to indicate a closed range of values (e.g., 1 Cor. 1–4; John 3:16–17). Inserting these dashes in Apple's Pages app is not readily apparent.

  • To insert an em dash (the longer one), press Option + Shift + -
  • To insert an en dash (the shorter one), press Option + -

Actually, these key sequences work across apps on Mac OS—I even used it in the WYSIWYG editor when writing this post!