This is a keyboard shortcut that saves you the hassle of reaching for the mouse, then fiddling with toolbar menus, every time you want to adjust the font size.
Here's how I roll on this:
1. Using your Home/End keys and/or the arrow keys, place your cursor at the start of the text you want to resize.
2. While holding down the Shift key, press the right or down arrow to select a character or enter line, respectively. Keeping going until you've selected all the text you want to resize. (Bonus tip: Adding the Ctrl key to the mix while tapping the right arrow selects an entire word at a time.)
3. Press Ctrl-] (that's the right-bracket key) to increase the selected text one point size. Press Ctrl-[ to decrease it accordingly. Repeat until the text reaches the size you want.
This sounds a bit more complicated and time-consuming than it is. Trust me: Once you start using the keyboard this way, you'll spend a lot less time reaching for the mouse--and dazzle onlookers with your Word finesse.