From http://www.mapleprimes.com/questions/201092-How-To-Insert-New-Paragraph-On-Its-Own by Carl Love:
I use these special keystrokes constantly in my Maple worksheet typing: Ctrl-J: Insert execution group below cursor. Ctrl-K: Insert execution group above cursor. Ctrl-T: Switch from executable code mode to text mode (for entering extended formatted comments). Ctrl-M: Switch from text mode to executable code mode. Shift-Enter (or Shift-Return): Begin a new line in the same execution group. Func-3: Split execution group into two (at cursor). Func-4: Join cursor execution group with execution group below.