When we do LT work, every boy on the team has an individual pace based on an average of their last few races. They know their pace to a range of 15 seconds (5:55 - 6:10) per mile or whatever it may be for each kid.
They also know that when I am standing at the mile mark (we have all the 400's marked on our course)if they are at 5:45 they will be stopped and I won't let them start until they get to 5:55. If they are grossly behind their pace, we pull them off. They aren't getting anything from the workout.
Teaching an adolescent pace is mind boggling hard. No idea why.
I borrowed this one from Coach Arbogast at Bingham...Usually once or twice a season we divide into groups of maybe 10 based on ability. We run 5 x 400m at 5k race pace on a 3 min interval. Each group has a prescribed pace based on 5k race pace. Every athlete takes their watch off for this one. I tell them all they have is 5 x 400m at 80 (or whatever the pace is). The trick is, it only counts if it is between 79.0 and 81.0. More than a second off in either direction it does not count. You can run several groups together, and make different athletes lead.
First time we did it, my top group was the worst, it took them 19 intervals to hit it. By the end of the season, just seven. Really just one interval to dial the pace in.
The groups love to compete against each other to see who can get off the track the fastest.