Skool Me On Synchro Function?

So 1st and 2nd gear was grinding in the little 64 Dart I brought home. I bought "THE transmission book" and sequentially scattered the tranny all over the work bench. All the synchro stop rings have nice, pointy teeth. A buddy says,"Synchros are weird. Look on the inside for wear on the groves." I look and the grooves on the inside that look worn are not on 1st and 2nd. The only gear that looked slightly worn was the points on 1st gear.

Would someone please explain (in small words) how a synchro functions? I'd really like to know! :D