Spacing errors creep into Word documents through copy-pasting and sloppy typing. Basic English grammar rules apply, and the spelling & grammar check should highlight these errors. I find it easier to first quickly check for spacing errors (and of course correct word spacing is required by the PAT rubric) before running a spell-check as follows:

1. CTRL + F to open the Navigation panel
2. In the search box, type two consecutive spaces
3. The number of instances of the string entered in Step 2 will be listed
4. Each instance of the string will be highlighted in the text
5. You can move from one instance to the next using these controls

The following combinations (and any others you can think of) should not appear in the document and as you enter the combination in the Search box you should see zero occurrences of each in the resulting search:

1. SPACE & SPACE
2. SPACE & ,
3. SPACE & .
4. SPACE & ;
5. SPACE & :
6. SPACE & !
7. SPACE & ?
8. SPACE & )
9. SPACE & ]
10. SPACE & }
11. ( & SPACE
12. [ & SPACE
13. { & SPACE