The only thing Donald Trump should be giving teachers is more school supplies -- so says John Salley, who tells TMZ Sports he ain't down with POTUS' idea to have educators packin' heat in the classroom.
We got Salley at an event at NeueHouse in Hollywood ... and the 4-time NBA champ told us only people trained to protect should carry guns, and no one else.
As for Trump's classroom cop proposition -- "I think teachers should carry books and pencils and pads. You know what, they've been lacking those."
FYI, the Education Market Association says teachers spend hundreds, if not THOUSANDS, of their own money on school supplies every year ... so Spider ain't wrong.