Easy and I've said it for YEARS! Teach every kid from Kindergarten - SIGN LANGUAGE!
Well that's not going to work because there are sign languages for various languages. An internet search shows over 300.
@Mackenzie Click-Mickelson, you beat me to posting the same thing. I was learning American Sign Language decades ago. But, it doesn't follow
spoken English with the same syntax. Words, verbs and phrases were switched around. Some words missing completely. (Anyone who has learned French with all their conjugated verbs and some verbs put before the noun knows what I'm talking about.

)
Add to that, there is a sign language that
does follow spoken English called Signed English, as well as those who just alphabetically spell out all the words instead of using gestures or symbols. Yet, either of those sign languages may not be understood by each other or those that do American Sign Language.
When I questioned WHY they didn't all sign the same way, or as we speak, or just have ONE universal sign language, it became very complex. Different sign languages developed as separate, complete and personal languages to the area, region and culture they originated. EVERY sign language is as protective and proud of their language the way we are with our spoken language.
Remember when the missionaries went to Easter Island and forced their language, beliefs, customs and religion on the people who lived there and in essence wiped out the previous culture, language, beliefs, and traditions? We do not know WHY the statues on Easter Island were created. Only theories. Forcing a single SIGNED language on everyone would essentially do that in a limited way.
And WHO decides which signs everyone uses? While an American gives the finger to someone, Italians have a different sign.

Yet, I guarantee you, when an Italian does it, there is probably no doubt what he did. "Did that guy just flip the bird at me in Italian?!?"

So why would an Italian need to learn the American way of doing it?
