English but louder = universal understanding?

Today at school we were doing an email session with Year 4. They were emailing a school in Norway that we have links with.
I carefully explained that they'd have to use simple language, no slang and ask lots of nice questions to get replies from the Norwegian children who were learning English as a second language.

One of the boys listened carefully and then put his hand up to ask:
"Should we do it in bold?"

So very bloody English. Shouting in an email so that Johnny Foreigner understands us.