Turn your sound on, then press play.
This rocket runs on fizz. You drop a piece of fizzy tablet into water, snap the lid shut, and a few seconds later the rocket jumps into the air. To see why, you have to look inside the tube.
When the tablet touches water, it starts to fizz. The fizz is thousands of tiny bubbles of a gas called carbon dioxide. That gas was not there before. The tablet and the water changed into something new. When materials change into a new material, it is called a chemical reaction.
Gas takes up far more space than the little tablet did. In an open cup, the gas just floats away. In a tube with the lid snapped shut, the gas is trapped. More and more gas squeezes into the same small space.
All that trapped gas pushes outward on every part of the inside of the tube. That push is called pressure. The pressure keeps growing until the weakest part gives up. On this tube, the weakest part is the lid. Pop!
Each press lets the tablet make more gas. Watch what the trapped gas does.
The rocket stands on its lid. When the lid pops open, the gas and water blast downward out of the tube. They push down, and the tube gets pushed up. This is called action and reaction. It is the same rule that moves a balloon rocket and a real rocket.
After the pop, there is no more push. The rocket coasts upward while gravity slows it down. Then gravity pulls it back to the ground.
Change is when something becomes different. One change often causes another. In your rocket, a tablet and water change into gas. The gas changes the pressure. The pressure changes a tube sitting still into a tube flying through the air. Keep an eye out for each change in the chain.
The fuel for a fizz rocket is water plus a piece of tablet. Small changes to the fuel make big changes to the launch.
A plain tube will launch, but an engineer can make it fly better. You get to add a nose cone and fins. Every choice you make is a trade-off.
The pop gives your rocket one quick push. A light rocket gets more speed from that push than a heavy rocket does. Paper, tape, and stickers all add weight, so use only what you need.
A pointed nose cone helps the rocket slip through the air with less drag. Drag is air pushing back against anything that moves through it. The nose cone goes on the closed end of the tube, which is the top of the rocket.
Fins keep the rocket pointing straight instead of tumbling. Use three or four, and space them evenly. Put them near the lid end, but keep them above the lid so the rocket can still stand flat.
Never put tape or paper on the lid. The lid has to open so you can load the fuel, snap shut tight, and pop open freely. Tape on the lid can turn your rocket into a dud.
The rocket stands on its lid on flat, hard ground. If it leans, it launches at a slant. If it falls over, it shoots across the ground instead of up.
Engineers test their ideas before they build. In this lab you launch a pretend fizz rocket. Change the fuel, launch it, and see how high it goes and how long it takes to pop.
The fair test rule: change only one thing at a time. If you change two things at once, you cannot tell which one made the difference.
Pop time is how many seconds pass before the lid pops. The lab speeds up the wait for you.
No two launches are exactly alike, so the same rocket can reach a slightly different height each time. That is why engineers test more than once.
| Launch | Water | Tablet | Temperature | Pop time | Height |
|---|
No launches yet. Press the green button to launch.
The building steps open when every mission is finished. Here is what you still need to do:
You earned it. Steps 1 to 6 happen at your desk. Steps 7 to 10 happen outside at the launch pad with your teacher.
Make sure the tube is empty and rinsed. Open the lid and snap it shut a few times. It should close with a click. A lid that is cracked or loose cannot hold pressure, so ask for a different tube.
Your rocket flies upside down from how the tube usually sits. The lid end is the bottom of the rocket. The closed end is the top. Stand the tube on its lid to see how it will look on the launch pad.
Cut out a paper circle about as wide as your hand. Cut one straight line from the edge to the center. Slide one cut edge over the other until the paper makes a cone that fits the tube. Tape the cone so it holds its shape, then tape it onto the closed end of the tube.
Cut three or four matching paper triangles, each about as long as your thumb. Tape them to the tube near the lid end, spaced evenly. Keep every fin above the lid. Stand the rocket on its lid to check that it sits flat and does not wobble.
Open the lid and snap it shut again. Nothing should be stuck to the lid or in its way. If tape or paper is touching the lid, move it now.
Write the name of your rocket on the tube. Then practice the launch moves with no water and no tablet: hold the rocket with the lid end up, pretend to drop in the tablet, snap the lid, flip it over, set it down, and step back. You will only have a few seconds on the real launch, so practice until it is smooth.
At the launch pad, put your goggles on. Hold your rocket with the lid end up and open the lid. Pour in water until the tube is about one quarter full. Wipe the rim and the lid dry with a paper towel, because a wet lid slips open too early.
Wait for your teacher to say go. Drop in the tablet piece. Snap the lid shut until it clicks. Flip the rocket over and stand it on its lid on the launch pad. Do all of this quickly and calmly.
Take five big steps back right away. Count the seconds out loud until the pop. Keep your eyes on the rocket and watch how high it goes.
Wait for the signal before you pick up your rocket. Guess the height by comparing it to something you know, like a door, which is about 7 feet tall. Write the height in your launch log below.
Remember the fair test rule. Change only one thing between launches, and write down what you changed. Write the height in feet.
| Launch | What I changed | Feet |
|---|
| What happened | Why | Try this |
|---|---|---|
| It popped but only hopped | The lid was wet or loose, or there was too much water | Dry the rim. Snap the lid until it clicks. Use less water. |
| It fizzed but never popped | Gas leaked out past the lid | Tell your teacher. Try a tube with a tighter lid. |
| It tipped over | The ground was bumpy, or a fin was below the lid | Find flat ground. Move the fins up. |
| It popped too soon | The water was warm, or the tablet was crumbled | Use cooler water and one solid piece. |
| It flew sideways | The fins are uneven, or the nose cone is crooked | Straighten the nose cone. Space the fins evenly. |
Write three or more sentences. What did you change on your rocket or your fuel? What happened? Why do you think it happened? Use at least two of these words: reaction, gas, pressure, force, weight, drag.
Big idea question: what changed inside the tube, and what other changes did that cause?
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