spelled or spelt? Which past participle should I use?

For those teachers who asked me this on the verb course last week, I have now done a little research around the subject.

In British English, you can use either 'spelled' or 'spelt' as the past participle.  As we thought, this is the same as the 'burned/burnt' and 'learned/learnt' participles that were on the Irregular English Verbs sheet. 

American English uses 'spelled' as the past participle because, in America, 'spelt' is more commonly used to refer to a type of wheat.

Hope that helps!