How do children think?

I bought a little fan for my son yesterday.why a fan!!?

Because he is very interested in rotating things, and, of course, it's exciting.But I was thinking with myself about the power supply of this device. Power Bank or something like that. Because my son could have put it into a usb computer, TV ،... but I was surprised that he find the Bluetooth speaker came from my gadgets and connected it to the fan.