Just a quick video showing how we want swimmers to push off during practice. When you here us say "proper drop-ins", this is what we mean. There is a progression to working on this with different age groups, but this highlights what we are working toward. 

Pushing off this way has a number benefits. One is to get an understanding of how to be fast underwater. This is also basically practicing the back half of a Butterfly or Breaststroke turn. Every single time kids push off the wall, they can "work on their turns" by simply pushing off the wall properly. Once they become good at this, they will be in a position to learn how to carry their underwater speed in to their breakouts.