1. and (The sentence is talking about a trend of more teenagers choosing to do something, so "more and more" fits the context of increasing numbers.)
2. families (Since the text mentions volunteering in the community, helping "families" makes sense.)
3. similar (This word fits the context where teenagers may do something like their Saturday job, which could be similar to voluntary work.)

So, the complete text would be:

Do you do the same thing every Saturday? It might be time to try something different. More and more teenagers are choosing to do voluntary work in their free time, and while they help their communities and their families, volunteering can teach young people important life skills, too.

Teenagers sometimes have a Saturday job or something similar, but in general, paid work is done by grown-ups, and in some countries...