I am keen for my son to learn a musical instrument when he gets a bit older. His gran would like him to play the cello, but I was thinking more trombone, or maybe the piano.
Some more food for thought.
What sort of boy is your son? To learn woodwind or brass requires a lot of effort and
daily practice. PIano you can get away with not practicing if you have some aptitude but wind and brass require you to develop an embouchure. This is basically a daily lip muscle workout. If you don't do it - you don't get anywhere. A piano can sound reasonably nice quite quickly. Brass and Strings usually (especially violins) take at least a year before you can listen without flinching. Guitar you can also get away with a lot but you do need to build up some finger callus.
What does the future look like? A big plus of the piano is that people
always need a pianist. It's easy to pick up extra £ at school or uni by accompanying people. Also learning the piano first, makes it easier to learn other instruments due to the complexity of learning to coordinate your left and right hands. I learned piano, then trumpet, then cello, then pipe organ with singing overlaid. I was retired from Cello as my parents ran out of money for lessons on that many instruments that I wasn't really practicing!
Take your boy to a music shop (if you can find one) and let him try some different instruments - he may get some opportunity to do that at school as well.
Finally, there are lots of good online resources for learning instruments, but a good teacher is still the best way. And it has to be a good teacher who clicks with your son. If he hates the lessons, the chances are you just have the wrong teacher. Find a different one - don't blame the child. We all learn differently and teachers teach differently. Some have not moved on from the Victorian period style of teaching. I was very lucky that my first teacher let me jazz up my pieces as long as I could also play them properly for her. My next teacher was awful. A Czech witch who would clip your nails and whack your hand with a ruler and only let me learn Fanny Waterman books (dire). I nearly quit at that point but my mum found me a different, more relaxed teacher who again encouraged me to both do exams but also to have fun with the piano. I've been playing for 45 out of 50 years now and do professional accompanying as well as a bit of cocktail piano etc.
