Breaststroke - 3 Fly 3 Breast

Obviously, this can also be a butterfly drill, but chances are you'll feel the adjustments, or at least the ability to vary your timing more easily in breaststroke than in butterfly.

Why do it:
For swimmers who are having a hard time learning how to vary, speed up, or slow down their rhythm in either breaststroke or butterfly, matching the rhythm of one stroke to the other can help.

How to do it:
1)  The key to this drill is the RATE in which you're taking your strokes.  Whichever stroke you start with, listen to the rhythm of that stroke and carry it through when you change the stroke.
2)  Start with three strokes of butterfly without breathing, then switch to three strokes of breaststroke, then back to three strokes of butterfly.
3)  Next, start with three strokes of breaststroke, then three butterfly, then three breaststroke.

How to do it really well (the fine points):
Figure out what you have to do to match the rhythms.  Going from fly to breast, you may have to shorten the strokes in breaststroke to match the rhythm.  Going from breast to fly, you may have to extend a bit more on butterfly.  You'll need to discover what you have to do to match the rates of both.  You can also add a pair of fins to this to really find the flow, but even though you can take two kicks for fly, limit the breaststroke to a single dolphin kick.

Side note:  This is an old standby drill used at specific times for specific swimmers.  This drill isn't for everyone, and at certain times in your development, what felt good at one point won't feel good at another.  I'd probably use this drill for someone in the earlier stages of swimming.  For those who are at a higher level, there's a much better way to stay stroke specific and work on detailed rhythm.