Anyone here join Yamaha junior music class for age 4-6? Is it good? What do they do in the class? I read their website say not teach musical instrument.

Build musical base for the child.
teach notations, sing, dance, play basic music (on keyboard/piano).
Generally is to build up the child's musical abilities and focus on hearing to get perfect pitch.
Keep in mind that parents must join in as well... so its also a class for parents...
Unker suffering now... every night kena practice music with my anaks.

So u think is it worth to send my kid? Like do they really learn something or it’s some hocus pocus stuff like the right left brain thing where u don’t see any difference ?

minimum thing ur child can get out of it is that he wont be tone deaf.
my anak seems to enjoy the music... but dislikes the practicing (which yamaha teachers are quote anal about).
It does help with building their confidence a little as they are required to have mini concerts for the parents and also perform solos.
Again, i must emphasize, its a parent and child lesson. The parent is required to attend class together and practice daily with the child.
If the child don't do well in class, the teachers will always put the blame on the parents. So get ready to be sounded also.
End of the day, its for your child. How good or successful you want them to be depends on you.

Do they teach singing like voice training and tone? Or just simply sing?

They teach to listen and sing in tune.

Cool! Then let my daughter try. Maybe next time can be singer.

I went to ask about the class over the weekend and the registration also need to buy some books. That 1 I ok.

Then other than the books also have cd and dvd. WHat is the purpose? My house don't have cd or dvd player is it can skip?

Need for practicing singing and recognizing the notes and stuff.
If parents not free to go through with the kids, at least they can watch the videos and listen to the songs to practice.
The videos are like those learning the alphabets videos in youtube... just another teaching tool.
If you dont have the players, you can rip it using your computer and transfer it to your phones or tablets. (disclaimer... we are technically not suppose to rip them due to copyrights issue... so i'm just providing a possible option. Anyway, if you have bought the CD & DVD, then u own the material anyway.)
Yamaha should have updated their form of media since not much ppl use DVDs and CDs anymore.

Yalo. I don’t even have the player how to rip lol. Just bought my laptop last year and now most don’t come with cd DVD player.

So the cd dvd is for self learning at home and won’t use in class right?

Yup.. wont use in class.