Could anyone musical explain this about transposing instruments please?

Maybe teacher moves them to a B-flat instrument at some point then they're set up ready for ensembles?

I was just coming to throw my tuppence in, but it looks like lanthanum has got there ahead of me.

It very unusual for a brass instrument to transpose in bass clef (except for the horns when they are playing extra low). And brass band tubas usually play in a transposing treble clef (The only instruments that play in bass clef in the average brass band are the trombones and tympani).

Definitely needs a word with the teacher...

(I'd be inclined to ask about some discount on his lessons, if he's now going to have to start over again on learning fingerings because they've taught him the wrong ones.)

Aah, that makes sense lanthanum. Hence they are effectively reading in F, a fifth lower, because on a B-flat instrument they'd be reading in C as expected. Well figured out!

Not a tuba player, but I think I may have worked out what is going on.

I think they have been taught to play an Eb instrument as if it is a Bb instrument. I think an orchestral tuba is most commonly a Bb instrument. When reading bass clef, tuba is not usually treated as a transposing instrument, so if reading a written Bb, that would be played with no valves down, and would sound as Bb on a Bb instrument. However if you then play the same thing on an Eb instrument, it will sound a fifth lower.

Ask your youngster how they would finger the arpeggio written CEGC in bass clef. If the answer is 4/13, 2, 12, 1, then my theory above is correct. If so, you need to have some discussions with the teacher, as the fingering they are being taught will never work if they play in an ensemble. Search Eb tuba fingering chart and you'll get the right fingerings for the instrument.

In brass bands, bass (tuba) players play off treble clef music, as transposing instruments, and they all finger a written C with no valves, and it comes out as Eb/Bb depending; the parts are labelled accordingly.

Stevie, it was in the OP, the C sounds F. And in the posted extract the B-flat sounds E-flat, which is consistent; and is played open which is consistent with it being an E-flat tuba. So they're playing an E-flat instrument using notation in F.

Get your dc to play a c, then find the corresponding note on piano. What is it?

Yep definitely tuba in E-flat and notation in F.

Whether that's common or not I'll have to leave to the tuba players! Do you happen to know what instrument his teacher specialises in?

The tuba part isn't written in bass clef, is it?

in short: it's complicated in the brass world

I come from an orchestra world, so trumpets (usually) are b notation, french horn and wagner tuba (usually but not always) in F, tuba and trombone as is.

the brass bands I played in played as is as well (because then you can just take any choral or piano or other instrumental music and play).

but at least the piano part is always 'as is' (maybe piano players are not as panicked when they see anything other that C?)

There are tubas in F. That's the same transposition as a French Horn in F but pitched a couple of octaves lower.

F tubas were/are mainly played by orchestral tubists. I think this is probably quite rare nowadays. I'm sure they play in bass cleff.

Your friend therefore may have an F Tuba!

The other question is, are you sure it’s an E flat tuba and not a B flat one? A B flat tuba will be able to play B flat and F without pressing any valves, whereas an E flat tuba without valves depressed will only play an E flat and a B flat.

Autocorrect fail - I don’t know what an E flat tuna is!

I am a tuba player and I will try and help! An E flat tuna will have a fundamental note of E flat (the lowest note that comes out without pressing any valves). When this tuba is played in a brass band it is written in treble clef and the E flat two octaves below middle C is written as a treble clef middle C. When the same tuba plays in an orchestra, it is written in bass clef and at actual pitch, so the note you hear is the note that is written. This is often - but not always - geographical as well; if you are in the brass band areas in the north of England in particular, many brass instruments will be taught using treble clef (“brass band notation”). If you’re elsewhere, the trombone and tuba will often be taught using bass clef actual (“concert pitch”) notation.
I hope this is useful!

Stevie, wouldn't brass band tuba be notated in treble clef? So I think we can rule that one out.

It certainly sounds like your tuba player is reading in F. Not a brass player so I will defer to those in the know as to how common that is.

What exactly does "noted in F mean", does it just mean that it is written such that when you play a C, it sounds like an F?
Yes exactly that.

If they in Eb you will play a minor third up. If Bb,move up a tone (i think..its been a while)

Orchestra tuba plays as is. Brass band tuba will be in Eb or Bb

(Thankfully I have string players and an oboe)

The piano part that comes with music books should not need to be transposed because it has been done by the publisher,

I think tuba plays 'as is'