OK Another question off of my other birthday party question...?

Should I invite his whole class (22 kids) or let him pick 5 (or however many) to invite? FYI I can invite a few individually and (hopefully) no one find out because each child has their own folder I could put the invited in. But of coarse the kids will probably talk about it. It just seems rude to me to not invite everyone but Im sure at least some parents would understand. OK, Now I'm just rambling. LOL Thoughts?