I tried this on a small group of 10-13 year olds. Most of them 'A' swimmers.25 FLY50 BK/BR75 BK/BR/FR50 BK/BR25 FLYAll on :30 per 25. It gave them enough rest to work turns.50 FLY75 BK/BR/FR100 IM75 BK/BR/FR50 FLYAll on :25 per 25. This made them have to go fast75 FLY/BK/BR100 IM125 FAST FREE !100 IM75 FLY/BK/BRAll on :30 per 25. I made them race each oneNow you take them back down the pyramid, starting with the 50 fly. End with a 25 ez (or sprint!) and you've got a mile of IM work.