If you are wanting to learn how to tumble turn or refine your current ability, here is an effective drill you can try. This drill will develop a better body position as you turn which will help to improve the speed of your transition at the wall.
Developing an effective breathing position when you are swimming freestyle is key in helping to make sure that you feel comfortable when you swim and also allows you to maintain your momentum from your stroking. This drill involves a strong kick to engage your body rotation.
Swimming good butterfly is about making sure that your kick and stroke are working in time with one another. Here is a great drill for you to try which will help develop the rhythm (timing) of your butterfly.
In breaststroke most of the power generated comes from your kick. To make sure that you are getting the maximum power and distance from each kick a tight streamline and good timing is imperative. The purpose of this breaststroke drill is to help with your timing while working a strong breaststroke kick to drive you forward.
The main focus in this backstroke drill is to make sure you are keeping a flat body position on the surface by maintaining a fast kick and a strong pull through the water with both arms. The further back your stroke enters the water the more power you will be able to generate when you pull through to your leg.