What is a Baby Soda Bottle?

Durable, clear Baby Soda Bottles have many creative uses as well as filling important roles in your science lab.

Over the years, Steve Spangler has popularized the name “Baby Soda Bottle” (or BSB) for this test tube look-alike. Thousands of these reliable plastic tubes have been used for valuable science labs as well as for science art projects in classrooms and homes everywhere. The first question everyone usually asks is, “What the heck is this thing?!” With a little research and a few hints, you’ll have that surprising answer very soon.

Experiment Materials

    No Products

  • Baby Soda Bottles
  • Various materials as needed (See "Take It Further.")
  • Adult supervision

Experiment Videos



Grab a BSB and take a close look at it. You are the proud possessor of the most durable “test tube” ever made. The catch is, however, it wasn’t originally intended to be a test tube. It has a secret identity.


Carefully notice everything you can about the BSB. What is it made of? Why is it called a BSB? How breakable is it? Why are the walls so thick? In fact, why are the walls thicker toward the bottom than the top? What are those threads that are around the top? Why does a Tornado Tube™ fit it so perfectly? What kind of cap fits on it? Now you’re thinking like a scientist!


Collect all of your observations and hypothesize what a BSB could really be. Before continuing, use the observations you’ve gathered and write that hypothesis so it answers the “What is it?” question.

Keep in mind that data will either support or not support the hypothesis. If the hypothesis for an experiment is not supported by the data, it doesn’t mean you’re wrong. Remember that it’s not about you and what you think; it’s all about the data.

How Does It Work

The hypothesis should be a simple sentence that offers a possible answer to the question of the experiment. It doesn’t include phrases like “I think…” or “I believe…” because the data matter most and they will either confirm the hypothesis or not confirm it.

The Baby Soda Bottle you studied looks like a large, clear, plastic test tube with cap threads around its top. Unlike ordinary glass test tubes, however, this thick-walled brute can be thrown into the dishwasher, dropped onto concrete, banged together, or stepped on and it just won’t break! The catch is that the name “Baby Soda Bottle” is not a trick name at all; they really are “baby” soda bottles.

In the plastics industry, the tube is actually called a preform. A preform is placed into a vacuum mold and heated. Hot, high pressure air is also blown into it and the soft plastic stretches like a balloon. It completely fills the inside of the mold which means the tube expands to about 40 times its original size. The plastic is cooled quickly, the mold is opened, and a new bottle falls out ready to be filled with a refreshing liquid. So, a BSB is actually a 2-liter bottle before it “grows up” into a big bottle. That’s why a cap for a 2-liter bottle (and other sizes) fits it exactly.

Take It Further

The preform, as you hold it in your hands, is perfect for use in a science lab or an art studio. You can use it for mixing, storing, collecting, analyzing, and observing all kinds of stuff, even though it’s really a soda bottle wannabe. Here are a few suggestions and these are – truly – only a few, too.

Liquid Laboratory – Use BSBs to collect samples of water from lakes, ponds, and streams to study later with a magnifying glass or microscope. You can, in fact, collect anything that fits into a BSB for later study in the lab or for storage.

Roots with a View – Grow plants in a BSB and see germination and sprouting firsthand. Fill a BSB with some potting soil and plant one or two fast growing seeds (grass, radish, lettuce, pea, bean, etc.) in each tube. Plant the seeds near the wall so you can watch the roots move down and stem grow up. Water only enough to keep it moist but not soaked. Transplant to a larger pot when the plant outgrows the BSB.

Wave Bottle – Fill a BSB 3/4-full with vegetable oil and the rest of the way with water. Add a single Color Fizzer Tablet (or a few drops of food coloring) and notice how it colors only the water. Seal the BSB with the cap. Tip the bottle back and forth to create waves of soothing, fun.

Time Capsule – Use a BSB to hold a secret message and hide it from prying eyes. Just don’t forget where you hid it! Use it to store facts and information that you will open and share at some point you choose in the future.

Sands of Time – Carefully place layer upon layer of colored sand in the BSB to make a colorful, permanent, layered rainbow of sand.

The Marble Challenge – Fill the BSB 3/4-full with clean sand, granulated sugar, or uncooked rice. Place a marble right on top of the sand. Cap the tube and find a way to move the marble from one end of the BSB to the other as quickly as possible. When you figure it out, make two or three more and challenge your friends. (HINT: A rapid upward jerk [straight up] followed immediately by a rapid downward jerk [straight down] moves the contents of the BSB around the marble.)

Popsicle Mold – You must use a brand new BSB and cap for this activity. Wash the BSB and cap with soap and hot water and rinse thoroughly. Fill the BSB 3/4-full with your favorite fruit juice. Place a clean popsicle stick into the juice and screw on the cap. Place the BSB in an upright position in the freezer (the BSB rack is the tool of choice here) and allow the liquid to freeze. BSBs are perfect for this activity since they won’t crack or break in the freezer. To release the popsicle, run a little warm water over the opened BSB and remove the frozen goodness.

Layers of Fun – A BSB is the perfect container to use when you’re building a column of density layers. Check out any of these activities: Seven-Layer Density ColumnColorful Sugar Water Density TowerBubbling Density Concoction, or Amazing 9 Layer Density Tower. This density experience will be even more interesting, much easier, and successful if you use a Baby Soda Bottle – Test Tube Rack to hold the BSBs.

Pop the Stopper – You must do this one outside since it makes a mess! Use a solid stopper that fits snugly into the opening of a BSB. Fill the BSB 1/4-full with water. Divide an Alka-Seltzer® tablet into quarters and drop one fourth into the BSB. Quickly seal the test tube with the stopper and point the stopped end away from all living things. Pow! The stopper goes sailing. Adjustments to water temperature, amounts of tablet and water used, and stopper pressure in the BSB will change the outcome greatly.

Erupting, Bubbling Blobs – Fill the test tube 3/4-full with ordinary vegetable oil. Add one capful of tap water to the oil in the BSB. Notice how the oil and water do not mix. Drop one of the Color Fizzer Tablets into the test tube, but don’t put a cap on it just yet. Watch what happens inside the BSB. After the blobs have stopped, fill the rest of the tube with oil until it’s almost overflowing. Now, cap the tube tightly. Tip the BSB back and forth and watch what happens. Blobs of colored liquid join together to make one big lava-like blob under the oil! Rock the BSB to create a rolling, relaxing colored blob inside the BSB.

Magnifying Glass – Fill the BSB to the very top with water and seal it with a cap. Place the BSB against some printed material and see how it magnifies the words under it. The shape of the water in the BSB bends light in such a way that it enlarges the print.

Color Mixing with Your Eyes – Fill three BSBs almost to the top with water. Add one Color Fizzer Tablet to each BSB to make blue water, yellow water, and red water. The fizzing is a chemical reaction occurring between baking soda and citric acid as they dissolve in water. The bubbles are carbon dioxide gas (CO2) and help to mix the color into the water. When the fizzing has stopped, add water to fill each BSB and cap all three. Hold each BSB to your eyes near a light to observe its color closely. Now, cross the yellow and blue tubes in front of your eyes and look through both of them at the same time. What color do you see where they cross? It’s green! Cross the red and blue tubes in a similar fashion to make purple. What color do the red and yellow BSBs make? What about all three?

BSB Twist – Stretch a rubber band around all three colored BSBs. Hold the tube trio up to your eyes and look at the light. What colors do you see? Now, slowly twist and turn the colors in the BSBs and watch the colors change before your eyes. Too cool! Count how many different colors you can see.

Color Mixology – Start with six BSBs. Three are the red, yellow, and blue BSBs you already have and three are empty. Pour some yellow (the lighter color) into one empty BSB and add a small amount of red (the darker color) to it. Pour some yellow into the second empty BSB and add a small amount of blue to it. Finish with red in the third empty BSB and add a little blue to it. These are the basic primary and secondary colors. You can make all kinds of shades and hues of them simply by changing the amounts you mix together. You’re mixing pigments in the BSBs. Mixing colors of light is very different.

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