Today

I went to one high school classmate’s home this afternoon. It’s a new building. And guess what? There is another classmate lives in a downstairs house. They are both newly moved in. What a small district. So we invited him up and watched a comedy movie together. I find the movie is funnier when you watch it with others.

Today

I visited a classmate of mine this afternoon, her/ his apartment is in a brand new building.

As chance would have it, another classmate of ours lives 1 floor down, it really is a small district.

So we invited him to watch a movie with us (comedy).

I always find movies are more fun when you watch them with friends (Happiness loves company) kind of like the saying "The shortest cut on a long journey is good company".

Today

I went to one high school classmate’s home this afternoon. It’s a new building. And guess what? There is another classmate who lives in a flat downstairs. They are both newly moved in. What a small district! So we invited him up and watched a comedy movie together. I find that movies are funnier when you watch them with others.

Today

I went to one a high school classmate’s home this afternoon. It’s in a new building, and guess what? There is another classmate living in an apartment/a unit downstairs  house. They are have both newly moved in recently. What a small world we live in! district. So we invited him up and watched a comedy movie together. I find the movie a comedy is funnier when you watch it with others.

some people insist on hyphenating 'high-school' when it is an adjective, as it is here, but it's not usual

'House' I think should be a single building or duplex or row of joined buildings, not a large complex of apartments.