Kids love balloons.  Balloons are fun and frugal entertainment.  There is certainly no denying that.

I always keep a stash of balloons around to pull out on days when my boys are in need of some unexpected fun.  They love to play the classic “don’t let the balloon touch the floor” game.

Balloons can also be a great science tool.  We used balloons to make our Marshmallow Shooters and for our Balloon Blow Up activity.

Recently, we’ve experimented with building our own model rockets and we’ve launched water rockets at our local science museum.  Rockets are fascinating and a great way to teach the concept of action and reaction.

Fortunately, they can also be as simple or as complicated as you’d like.  Today, simplicity was the route we took.  By using a few items we had around the house, we made balloon rockets.

What you need:

• Piece of yarn (cut to about 6 feet)
• Balloon
• 2 Chairs
• Drinking straw
• Tape
• Scissors

Start by tying one end of the string to the back of a chair…

Thread a drinking straw onto the other end of the string, and then tie the string to the second chair…

Attach 2 pieces of tape (about 2 inches in length) to the center of the straw…

 Next, inflate a balloon (Don’t tie the end!)…

Holding onto the opening of the balloon (so the air doesn’t escape), attach it to the straw using the tape…

 Pull the balloon to one end of the string (so that the opening of the balloon is touching one of the chairs), and let go…

Observe what happens.

The balloon should start to move as soon as you let go of it.

Action and reaction is a fairly simple concept –  To make an object move one way, a force has to work in the opposite direction.

In this case, the balloon is full of air.  When you let go of the balloon, causing the air to rush out of the opening, it creates a pushing force in the opposite direction.  This makes the balloon move.

Real rockets work in a similar way.  A rocket engine works by exploding fuel inside a chamber that is open at the bottom.  The force of the explosion creates an opposite force that pushes the rocket up and into space.