To try to help you learn and improve your tumble turns here are some ways to practice. It will help you to improve the turns if you practice the different parts and then put it all together:

1. Practise pushing from the side and doing a somersault
2. Now try swimming five strokes and then doing a somersault
3. Now swim towards the wall and do a somersault putting your feet on the wall as you go over.
4. Now practise pushing away from the side underwater and streamlining (flat and thin with one hand on top of the other)
5. Once you can do this try adding a leg kick and then starting to pull as you reach the surface.
6. Finally, put the whole thing together - swim, tumble, push off, streamline and swim

Now you have got the whole thing working, try practicing it every time you swim front crawl. You will soon find that it becomes smoother and quicker.