I bought my youngest a bass just over a year ago along with 20 lessons and he has really taken to it.
The current situation has veered him onto learning the old fashioned way i.e. put the 'record' on and keep going until your guitar sounds like the one on the record. He is set to resume his formal lessons once things get back to normal but I would sill very much like to encourage him to plug away with what he's doing now until then and beyond. He's looking for song suggestions, classic bass guitar parts to work on and despite being a six string play with a fair few years under my belt I (somewhat embarrassing) am not sure what to recommend.
I'm also trying to get him into the habit of learning and playing the whole song and getting familiar with the verse/chorus/bridge structure rather than just learning 'the 20 best rock riffs' off of youtube. He does have a few down in this way already - Come Together, Billie Jean etc
He's a fifteen year old and generally agnostic when it comes to genres.
I would be interested to hear any suggestions.