junior high school or used to

When I was in junior high school, I used to play soccer with my friends.

'Junior high school' is the school you go to before senior high school.  It is usually for grades eight and nine and is frequently shortened to 'junior high'. We use 'used to' to talk about something that was a repeated action or state in the past that is not true now. Notice the following:

1. He was very popular in junior high school.
   
2. He used to have problems talking to girls.
   

plastic papers or bind them

We used to collect plastic papers and bind them with string.

'Plastic papers' are papers that have been covered in plastic so they're more durable.  To 'bind' things together is to attach them to one another, in this case like a book. Notice the following:

1. We need to make some plastic papers for the convention.
   
2. Make sure to bind your notes so you don't lose them.
   

ingenious

That's very ingenious of you to make your own ball.

An 'ingenious' solution is one that is clever, imaginative or resourceful.  It is not a common thought or solution to a problem. Notice the following:

1. She always has very ingenious ideas for new products.
   
2. I think that is an ingenious plan.
   

to tell the truth

I was not very good at playing soccer actually, to tell the truth.

We add the phrase 'to tell the truth' when we want to make an honest statement that may not be very popular, but it is how we really feel.  Notice the following:

1. To tell the truth, this isn't the best way to solve the problem.
   
2. I don't think you would be the best person for the job, to tell the truth.
   

bummer

It's a bummer that you can't play anymore because everyone's busy.

We use 'it's a bummer' as mild slang to mean 'it's a disappointment', 'it's sad' or 'it's terrible.' Notice the following:

1. It was a real bummer that it rained every day of vacation, but we had fun anyway.
   
2. It's a bummer that you broke your ankle and can't play soccer this year.