You can try by giving him his work back and saying,"You've made three spelling mistakes there.

She's hard on people who make too many spelling mistakes!

I found a spelling mistake in our editorial this morning.

The spelling mistake had nothing to do with the special character.

But still the spelling mistake at the beginning, please i..

Just a few spelling mistakes and slips, such as there generally are in automatic writing.

There is the one spelling mistake, but you're definitely improving.

Sorry, I made a spelling mistake in my last line.

Well it's a good letter but your spelling mistake.

Which always looks like a spelling mistake to me.