Knowledge: Senior communities offer classes for grandma and grandpa to attend and learn about many things. On the other hand, elders can enjoy swimming courses at the local sports center for free.

Conversation:
I love to swim and it keeps me in shape.
Nice!  It's a good "low-impact" sport, compared to running.
Yes and I have lung disease its very easy for me to exercise in water, much easier than a gym workout
Oh I see! And swimming is also useful for survival, right?
Yes and its also low impact on my bones and joints. Older people really benefit from swimming.
Swimming is low-impact because the human body is only slightly less dense than water, which allows the water to support a person's weight.
Oh ok that makes a lot of sense. Do you know a class for my grandma to attend?

Response: Sure. Your grandma can attend swimming classes at the local sports center for free.