Why drills? Best thing you can do is teach them how to accelerate: wall drive, push up starts, hop starts, resisted partner pull/release, block starts. Range from 10-30m. Then, spend time on max velocity with some short fly sprints: 30m run-in and a 10m timed zone. Then, some speed endurance in the 40-60m range. Weight training would be good and/or explosive medball. Maybe some hurdle mobility drills. Plyometrics – bounding, hopping, skipping and box jumps. Hurdle hops. All of that would be better than a bunch of butt kicks, agility ladders and drills IMO. In short, I don’t think you can drill your way to speed. You get faster by sprinting fast, getting stronger, increasing overall fitness and improving technique. I’ve seen many “speed” camps and most don’t have much to do with speed at all. More like quickness and agility camps, which doesn’t have much application to linear track speed. Hope this helps.