Put a cone at each 100m. Don't tell them the time for the total distance, tell them the time per 100m. Use odd distances like 700 or 900 so they focus on the cones.
I have done this with tempo runs too - I had a ~2000m loop and set out cones every ~500m. The athletes ran for time - so, every kid regardless of ability would run for 22 minutes, and they all had 'cone splits' to hit.
I have used this and it works really well - although if you do it too much if can backfire and take away the 'feel' aspect. They run too fast or slow despite how they are feeling.
Another key thing to do is to remind the athletes that if they are supposed to be running 1600m repeats @ 6', then that is 45" per 200m. So if the first 200m split is 40, then their adjusted pace for the total rep should be 5'55 or if the first lap is 50, then their adjusted pace should be 6'05. Cones again helps with this.