This experiment is for anyone who like to make simple rocket using Balloon. Here we shall try to make Balloon fly in straight upward direction and learn about Newton's 3rd Law of Motion, Thrust and Stabilizer concepts in rocket.

Teachers can also arrange competition so students can vary the design to achieve pre-defined trajectory or goal to hit any target on roof.

Step 1: Raw Material Required

Following things we would need to perform / make Balloon Rocket -

Balloon
Unused Marker Pen
Paper Cup
Masking Tape
Scissor
Pen

Step 2: Attach Nozzle ( Marker Pen Tip Holder) to Balloon

Remove marker pen tip holder from marker pen and insert into balloon as shown in picture.

Note that conical portion is coming out of balloon opening. This forms passage for air to come out.

Air coming out of balloon provides thrust to our Rocket (Force to push rocket upwards against gravity).

In real rocket , this is achieved by burning fuel. Gases escape out of nozzle, create thrust to push rocket upwards.

Step 3: Prepare Base for Holding Balloon

Take one Paper cup and cut it into two parts (cut out 3/4 portion).
Also cut three legs as shown in picture. The idea is to reduce weight.

In real rockets, every gram counts. Increase in weight means more thrust / force require to push rocket out of Earth's gravity. We have to keep a watch on how much weight we are adding to our Rocket.

Step 4: Prepare Flaps / Fins for Rocket

Prepare three square cuts from left over paper cup as show in picture
Fold them into half and stick them to base of rocket with the help of masking tape.
Note that those must be placed symmetrically.
Make a whole in a base of cup as shown using pen.

You can make another model without these fins and observe the Rocket performance.

Step 5: Attached Nozzle to Base

Insert nozzle (attached to balloon) inside hole of a cup base (See picture)
Use making tape to secure the nozzle to rocket base.
This makes whole assembly and our Rocket is ready to go.

Step 6: Variations (4 Fins)

You can also try to make use of 4 fins and see what is outcome.

Step 7: Now Time to Fly Your Rocket

See video to check out how it is done.
Blow air inside balloon from nozzle and place finger on opening so air would not come out.
Place balloon so it would be facing upwards and now gently remove finger from nozzle.

Observations -

Try to check how Balloon flies when you don't have Nozzle and Fins attached. You can observe that balloon goes here and there without any specific direction or trajectory.
When we attach Nozzle and fins to rocket , it is observed that Balloon flies upwards properly (showing straight trajectory, mostly upwards if you keep nozzle pointing down).
By using this experiment we can understand that how rocket (real one) uses thrust ( in our case air coming from nozzle) and fins / stabilizers to achieve upward trajectory of Balloon.
We can also understand Newton's third law of motion about equal and opposite reaction (Air coming out of balloon helps it to move upwards)

Pro-Tip :