Kids Riddles

I can go through glass without breaking it. What am I?

I am as simple as a circle, worthless as a leader but when I follow a group, their strength increases tenfold. By myself I’m practically nothing. What am I?

I can only be played on a windy day. What am I?

I twist and turn and leave a loop. What am I?

I save lives on the ground and in the air. What am I?