Playing octaves on the piano can seem a bit difficult at first because the distance is large - especially if your hands are not very big yet. To play octaves more easily, try to think of them like any other interval. For each interval, your hand has to learn how far the distance is between the notes. Just as you probably know what a second or a third feels like and can almost automatically reach for the next note, you can learn what an octave feels like. Sometimes you may play octaves together as a chord. In other places, the octave interval is two notes that are played one after another. Playing the notes together is more difficult because you have to stretch to play both notes at the same time.
Before you start playing both notes of an octave together, see if your hand is big enough to comfortably reach the distance. If you have to strain to reach both notes, your hand may need to grow a bit more. In this case, you can break up the octave - play a short lower note and then jump to the top note and hold it for the rest of the note value.
Hands and Wrists
When playing octaves, remember to keep your fingers firm, and your wrist relaxed. The finger joints should be slightly curved as if you are holding a basketball. Keep the main part of your hand about a half-inch to an inch above the keys. Be careful because octaves can sound sloppy if you accidentally press down on the keys in between with your hand.
Make sure that your wrist is level with your hand for good balance and control. Play an octave and then close your eyes and think about how it feels. What is the distance between your thumb and pinky? How does your wrist feel? Put your hand back down in your lap and bring it up and play the octave again.
Repeated Octaves
Many pieces have lots of octaves in a row. This is not as difficult as it looks. Once you learn the basic technique for playing an octave, repeated octaves are simple. Your hand position stays the same, although the wrist movement changes. Move the hand up and down slightly - just enough to press down the keys - and then release them.
If your whole hand flaps around with excess motion while playing octaves, your arm will become tired and tense, Practice repeated octaves slowly at first and gradually speed up. You can also practice scales in octaves.
Final Tips:
1. Start slowly so your hands get used to stretching for big intervals.
2. Relax your hand, wrist, and arm muscles when you play octaves.
3. Find balances in your hand and arm on each octave. It might feel a little awkward at first but you should not feel as if you have to work extremely hard to play them. If something hurts, stop and talk to your teacher.