[tmaly]

I can think of three great options for age 11.

First option get a makeymakey and work through the free project videos on their site.

Second option get a microbit and work through the free tutorials on makecode. If you have two microbits, they can talk via onboard radio. They also have Bluetooth so you can connect to a phone.

Third get a copy of the Getting Started in Electronics RadioShak book and build some of the science and circuit projects.