Ideal training plan, IMO:
*This plan with the expectation that he will be racing at least once a week, though for high schoolers its often twice. For the sake of argument, let's say he's training for meets on Saturdays.
Monday: Speed session, 400,300,200 x (4-6 sets) with 1-2m recovery b/t intervals and 3-4 minutes b/t sets.
Tuesday: Recovery day - 50-60 minutes at easy pace with abs/core exercises after (pushups, sit ups, planks, etc.)
Wednesday: Endurance/strength training - 4-5x 1000m at 3200m - 5k - pace depending on how aggressive we want to be with his training regimin and race schedule.
Thursday - 45-60 minutes depending on how sore/tired the individual is. Higher end if his legs are feeling fresh, 45-50 if he feels worn out. Finish with strides and core.
Friday - pre meet, 35-40 minutes easy shake out. 4-6x 100m strides with drills and simple abdominal work.
Saturday - race. Win shit.
Sunday - long run, 75-90 minutes increasing as individual's fitness progresses.
Wash, rinse, repeat.