How can spell checking be turned off for a portion of a OneNote page

A variation on the language support trick from Petri above seems to do what you want:

1. Select a block of text in your document that you want to disable for spell checking
2. Go to the Review tab and select Language > Set Proofing Language
3. Select a language for which you and your likely readers have no dictionary, e.g. Afrikaans, Cherokee etc. work for me.

The other text will still default to being in the original language, e.g. English (UK) in my case and will still be spell checked as normal.

You can also keep the proofing language pane open to make it quicker to apply the same change to multiple areas of your document.

I guess the reason for this functionality is for when you quote something in another language, you can spell check it correctly.

Install OneTastic addin, which has one of macros, named "No spell check"

http://omeratay.com/onetastic/

http://www.omeratay.com/onetastic/?r=downloadMacro&id=1DF08B3C629840759A86237CC090F8A9

Works perfectly

P.S. Onetastic is an add-in, which is made by Microsoft OneNote team developer, and has lots of useful features. You can trust it.

I'm afraid this is not possible. In order for this to happen, a OneNote page would have to be come much more complicated, there is no way to 'fine-tune' spell-checking that specifically.

However, you can tinker with the spell checking options in Tools -> Spelling -> Spelling Options:

Try experimenting with some of the highlighted options above. For example, you can have it suggest words from the main dictionary only, or use a custom dictionary, or even edit the word list yourself...

You can also disable spell checking or only have it check it in one sweep. To have it check in one sweep, uncheck Check spelling as you type.