After you open the presentation whose spelling you want to check, click the Spelling button on the Standard toolbar to launch the spell check.
If PowerPoint finds an error, it highlights the misspelled word and opens the Spelling dialog box. Click the correct spelling in the Suggestions list and click the Change button.
PowerPoint corrects the error and moves to the next one. If the flagged word is correct as is, click Ignore to skip this instance of the word (or click Ignore All).
PowerPoint continues flagging errors; change or ignore them as necessary. When PowerPoint indicates that the spelling check is complete, click OK.
INTRODUCTION
Any text in a slide that appears with a red wavy line under it indicates a misspelled word or a word that isn't in the Office dictionary. This enables you to immediately see whether a word you typed is misspelled. In addition, you can use PowerPoint's Spelling dialog box to check for errors in your presentation.
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No Usable Suggestions?
If none of PowerPoint's suggested corrections is the one you need to correct an error, you can correct the word yourself. Click in the Change to list box, type the correct word, and click the Change button.
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Checking from the Beginning
You don't have to be at the beginning of a presentation when you check for spelling errors. If you start in the middle of a presentation, PowerPoint automatically continues at the beginning of the document.