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I’m talking about what happens when you combine vinegar, baking powder, a balloon, and a curious mind. The specifics are:

Safety glasses. One day you’ll need to wear a whole lot more than these to do an experiment, but for now protect yourself from spills, splashes, and exploding balloons. Swimming goggles will work, too, but protect those eyes! Always. Vinegar. Any kind will work; I used plain old white vinegar. Baking powder. Measuring spoons. n Measuring cups, calibrated droppers, anything that you can measure liquid with (you can usually get 5-ml droppers from the pharmacy for free). A piece of paper rolled like a funnel. This is for quick dispensing of the premeasured baking powder–and you’ll need to be fast! A small glass, a cup with a spout, or anything that will easily pour premeasured liquid. Chart with five columns—Experiment #, Vinegar, Baking Powder, Time, Size. You can have as many rows as you wish, because since you’re numbering your experiments you can go on for as long as you have materials! Plastic bottles with mouths small enough for the balloon to fit over (and for you to pour liquid into without it spilling)—as many as you want, but five is a good number. Pre-expanded balloons, at least one for each bottle. These things can and will pop, so test them first by blowing them about halfway up to make sure they don’t have any holes. This also stretches them out. Masking tape to wrap around the expanded balloons so you can accurately measure them.

Now start having some fun.

1. Write "1" in your experiment column. You’ll make adjustments based on this first experiment, and it’s important to document what you’ve done, no matter what. Write it down!

2. Put a tablespoon of baking powder in the paper funnel, laid on its side. Write down how much.

3. Take a tablespoon of vinegar and put that into the small cup. Write this down.

4. Test the balloon on the mouth of your plastic bottle by fitting it over the top. Better for it to break now than later! Write this down. Whoops . . . no space? Well, experiments are all about observing procedures, and how can you repeat a procedure if you don’t know what it is? You can’t. So make another test column—or a new chart with another test column. That’s another thing experiments are all about—revision.

5. Pour the vinegar into the plastic bottle.

6. Get the balloon ready. . . .dump the baking powder in, and as fast as you can, put the balloon over the mouth of the bottle.

7. Watch the contents of the bottle bubble away, and watch the balloon expand. You might also want to watch the clock at this point to see how long it took for the balloon to start expanding. Give the bubbles a few minutes to calm down, and see what you have left. Is there extra baking powder at the bottom of the bottle? Maybe try some more vinegar this time? Sounds like Experiment # 2.

You could get pretty complicated with this, explaining reactions, drawing the formula for the process, measuring the balloon expansion with tape, predicting how large the balloon will be for a given experiment, and so on. . . . Or you could just watch a balloon expand without blowing a single breath!

—Jennifer White