Taking the simple straw rockets we expanded a bit to make our own since the straws we buy at the store don't come with paper wrappers.
You'll need a straw, paper, tape, and paper clip if you'd like.
Wrap the paper loosely around the straw and finish off with some tape. (you might need some help for this part)
Fold the top down and secure with tape or a paper clip.
You can create fins with extra paper for the end of your rocket (would be fun to see how the fins change the rocket's flight)
When you're ready to launch put your rocket on your launcher and blow!
As always make it your own by changing it up a bit. Use less paper, different paper, less fins, more fins etc.