As a musician I would suggest giving a "real toy instrument" to your son such as toy drums etc. -- it will allow him to form an early understanding of how objects produce sounds (i.e., bigger cavity = lower sound, pressure on surface = higher sound, etc.)
Dude. There is one piano, 2 xylophones, one accordion, three real hand drums, several Remo kids drums, two kids violins, and assorted small percussion around the house.
There are no plastic electronic drums, keyboards or other things that say letters, squeak, or otherwise make non-real noises.
At extra special times, all three of them will parade around the house with drums and sing Whiskey in the Jar. It's quite an experience.
But as for the electronic bits, He just likes the ipad. All three of the kids do.
Kids usually get tons of stuff and will at one point or another own many real instruments. There is nothing whatsoever wrong with them also playing with tablets.
