Ballet or keyboard?

Ballet counts when you start doing grades, so the higher grades really which is teens. I only mentioned it to show it’s value other than the skills, but I’ve no idea about drama equivalent.
My point really was that for now all hobbies are for fun, and children change and grow and sometimes like it and sometimes don’t. It’s great to have a variety of opportunities to develop a well rounded and happy child, but some hobbies can continue for years and so be prepared to put the effort and expense in if you find the right one.

Does she actually enjoy drama? I’d say both ballet and piano are more beneficial than that, and the dance side also promotes confidence and performance like drama does but has more emphasis on strength, skills, posture and the grades count towards uni points eventually.
Piano works the brain very differently and helps with maths, dexterity and is a nice skill to have if you can stick at it.
Four is young for both, but they are both long term commitments if they like it and stick with it, so not too young. My children both started dance at 3 and my youngest was 4 when she started piano. Bear in mind though that they both are a big time and money commitment too, especially when you add in extras such as show feed, exam fees etc.

This.

Don't start anything new in the first term at school - let her settle in and then see how it goes.

4 is young for keyboard - is the teacher experienced with this age-group? Mine started piano at 6, and her teacher suggested a taster lesson before committing, to see whether she was ready. Some are ready younger; for some it's later - I started at 6 and gave up, and started again at 8, when it went much better - it was also with a more experienced teacher. To get most out of learning an instrument, there needs to be regular practice between lessons, so you have to be sure you can fit that in too - which may be difficult if she's in after-school club on some days.

She's already doing two physical activities. I'd lean towards piano (unless she screams nooooooooooooooo) because it's about dexterity, rhythm, maths, reading, communication, etc, etc and is done sitting down. And it's music. Which is cool.

@earpods yes in my experience it's far more exhausting, everything they are learning is new, they are surrounded by new people so are ill all the time 'Reception Flu' much like 'Freshers Flu', expectations on them are higher.

I wouldn't underestimate how important factoring R&R is now. If you do fill her time (as I did as she seemed fine) when you get to a school holiday they just crash.

Keyboard.

She already does two physical activities.

A musical literacy will set her up well for other areas in life.

Depends what's she's doing after school... if she's going to after school care like childminder or at school then it will be a long day.

If she's going home at 3 she might have more energy

In my experience, yes. Much more tiring.

She's much too young for keyboard. At that age only Suzuki method on a small instrument like a half size violin makes any sense. There's not really much point starting piano until she's bigger, stronger and reading confidently. Ballet has most of the benefits of Suzuki: discipline, rhythm and musicality with the added bonus of exercise.

You may find she can do ballet and keyboard at school. My DD did. Although she didn't start keyboard until Y2.

As someone who did both she’s far too young for keyboard lessons. I know, I know! There is the odd prodigal child who’s grade 8 piano before they can talk but at that young age I’d go with dance.

I would also knock drama on the head for a few years and take her to hose riding lessons. There will be plenty of recitals at dance class

Ballet is all skipping about pretending to be fairies, teddy bears and soldiers at that age anyway. It does introduce them to classical music though, helps with rhythm, co-ordination, balance, listening to the teacher and taking turns, so it is worth a go.

Keyboard - at 4, their hands are probably too small. Unless you already have a keyboard or piano at home (and people who play it), then it's not really worth it.

@earpods OP If I were you, I'd find a ballet class at a suitable time and ask if she can have a trial lesson before the end of term to see how she gets on. Some like it, some hate it, and you'll soon find out!

Ballet will snowball to tap, street, acro, modern...... And sounds like it's already covered in another group.

She is doing enough right now and school is exhausting. I would keep that day as 'friends day's and have that as the day you have playdates and help her develop her social skills at home and that she can rest. Alternatively enroll her in Rainbows or Cubs, that ways she's exposed to socialising and lots of activities.

Swap swimming for keyboard when she is competent

I say the above as mother whose child was scheduled for activities after school everyday and we didn't stop until COVID made everything stop. Do not fill every minute, it will do neither of you any good, I'd keep it to a maximum of -
1 x Physical activity
1 x Group activity
1 x Arts activity

These will change over the years and seasons for example DD plays rugby September - April then watersports in the summer.

Too young for music lessons; wait a couple of years. There might be offers of other instrumental lessons through the school in any case, which would enable her to join ensembles.

Swimming, drama plus starting school is enough unless she's expressed a desire to try something. Don't fill her time just because you can. It's no bad thing to a) have chill-out time and b) understand dealing with a little boredom from time to time!

Schedule in unscheduled time. If I am ever asked what I would do differently if I was to start child rearing again, I always say fewer extra curricular things

Why not just have a walk, chat, play silly games, get her to help tidy the cupboards (!), make a scrap book, watch the birds, song songs….loads of other options!

Four is too young for ballet really- but music and movement is all good. She’s really too young for piano too.

I'd go for ballet. My DD started toddler ballet at age 3 and is still going 10 years later, working through the grades. Her PE teacher at school has remarked how strong her legs are and she loves performing in the dance school's shows, it's brought her confidence on a lot.

She’s doing enough already.

Two additional activities plus starting school is more than enough at 4.

Does she have to? Don’t underestimate how tiring school is.

Definitely keyboard. I think ballet is fairly useless, personally.