4th And 5th Finger Trills

In Beethoven's Moonlight sonata Mov 3, there are parts where you must hold an octave with your thumb and 4th finger, while playing a trill with 4th and 5th fingers. This is almost impossible for me due to my small hands. I can barely reach an octave as it is and if I have to do a trill on top of that.... is there a solution to this problem?

Just pretend to hold your thumb! The best solution is usually the simplest and the most pragmatic. AFF

When you play the octave, if you literally hold your thumb note, you are effectively playing a finger isolation exercise (which up to speed, will probably never work for you). This is because, while your trilling fingers (4th and 5th) need to be supported by the arm, you're too busy balancing your weight on your (non-playing) thumb. . In fact, play it . ~ There is a huge problem with what you have written here. Let's start with: "must hold an octave with your thumb and fourth finger" Correction: Must you are holding the octave. This is where the pedal comes in. And yet, the octaves are not marked legato, so there really is no reason for you to feel so obliged to hold the thumb note. Relax! It's not as hard as you're making it! ~ And this leads me to the final, and biggest problem with what you wrote: "while playing a trill with 4th and 5th fingers." WHO SAYS WHAT FINGERS YOU USE TO TRILL? I'll answer that question for you: YOU decide what fingers to use. No one else. Be smart with your fingering. Everyone knows 5th-4th finger trills are a recipe for disaster. Most professionals would never finger a trill with 4 and 5 unless absolutely necessary. I never learned the piece, but I'm looking at it right now. Here's what I see: For the first A-sharp octave trill (initial octave is in bold): 535323 5 (On first sight, that's what seems most reasonable to me. There are MANY options though). For the next one, F-double-sharp: There's no way for someone with small hands like yours to hit a white key octave using 1 and 4. In fact, for most human beings, that kind of fingering in a rapid passage is not a good idea. So first and foremost, you start the initial octave off with the 5th finger. Try this: 323212. You probably think it looks odd. But it's a totally normal fingering. You quick get your thumb off its note, then "cross" your third finger over your fifth (a la Chopin op. 10, no. 2), which brings you into a 3-2- trill. On the final 2nd finger F-double-sharp, you play it staccato and then move to the sforzando G-sharp octave. ~ If there is a main point to all of this, it is that you must allow your thumb to follow your finger hand and arm. Do not stretch the thumb out in the direction of your hand's activity! Oh yeah, and there are no "musts" when it comes to fingering. Get that out of your head fast.