Few experiments surprise children as much as the bouncy egg. You start with an ordinary egg, leave it in a jar of vinegar and a few days later you have something rubbery, squishy and see-through. It is a perfect “wait and see” project, and it teaches observation, patience and predicting.
This guide takes you through the bouncy egg experiment step by step, with a simple explanation of what is happening, safety notes for working with raw egg, troubleshooting tips and ways to make it a real science investigation. It is one of the experiments in our wider kitchen science experiments for kids guide.
What you will need
- 1 raw egg per experiment (more if you want to compare)
- A clear jar or glass tall enough to cover the egg
- White vinegar, enough to cover the egg completely
- A spoon for lowering the egg gently
- A tray or towel to catch any spills
- Paper and a pencil, or a science journal, for predictions and notes
- Optional: a ruler and a piece of string to measure the egg before and after
Before you start: handling a raw egg
A raw egg is an ordinary ingredient, but it needs a little care.
- Wash hands with soap and water before and after handling the egg.
- Do not taste the egg, the vinegar or anything from the experiment.
- Keep the jar away from food and away from reach of pets and very young children.
- Skip this experiment if anyone has an egg allergy. Even touching a raw egg can be a problem for some people.
- Clean surfaces that touched the egg with warm, soapy water.
Step-by-step instructions
Step 1: Make a prediction
Before you put the egg in the jar, ask your child what they think will happen. Will the egg float or sink? Will it change? How will it feel afterwards? Write the answers down or draw them. There are no wrong guesses, and the predictions are a big part of the fun when you look back later.
Step 2: Look at the egg closely
Hold the egg and describe it. What color is it? Is it smooth or bumpy? Does it feel hard? You can measure around the middle with string and a ruler and record the number so you can compare later.
Step 3: Place the egg in the jar
Use a spoon to lower the egg into the jar gently. Pour in enough vinegar to cover the egg completely, and watch. Small bubbles usually begin to form on the shell almost straight away.
Step 4: Observe in the first hours
Ask your child to look and draw what they see. The bubbles are gas, and they show that something is happening on the surface. The egg may float up and sink again as bubbles gather. Place the jar on a tray in a spot where it will not be knocked over.
Step 5: Wait and check each day
After about a day, you may see a layer of foam or scum at the top, which is normal. Take a daily look and add notes. After one day many people replace the vinegar with fresh vinegar, which can help the shell dissolve more evenly. Use a spoon to lift the egg out carefully if you want to check its progress.
Step 6: Rinse the egg gently
When most or all of the shell has gone, usually after roughly two to three days, lift the egg out and rinse it under cool running water. Rub gently with your fingers to remove any remaining bits of shell. Do not scrub hard.
Step 7: Explore the finished egg
The egg should now feel rubbery. If you hold it up to a bright light such as a phone flashlight, you may see the yolk inside. Compare the egg’s size to the measurement you took at the start. Many families notice that the egg has grown slightly, and the next section explains why.
What is the science?
Eggshells are made mostly of a mineral called calcium carbonate. Vinegar is a weak acid. When the two meet, they react and produce carbon dioxide gas, which is what forms the bubbles on the shell. Over time, the reaction wears away the shell.
Under the shell is a thin, flexible membrane that holds the egg together. The vinegar does not dissolve it as quickly, so the egg stays in one piece even without its shell. That is why it feels rubbery.
Some families also notice that the egg gets larger. A simple explanation is that water from the vinegar can move through the membrane into the egg, though the details are a topic for older children to look up. For young children it is enough to say: “The egg soaked up some of the liquid.” If you want a connection to another reaction you can try, the baking soda and vinegar volcano experiment also involves an acid, vinegar, making gas bubbles.
Questions that turn it into a real experiment
Once your child has made the first egg, they can change one thing at a time and compare. Try these:
- What happens if you use two eggs in two jars, one with vinegar and one with plain water? Which one changes?
- Does the egg float or sink at the start? What about at the end?
- Does the egg look different when you hold it up to a light?
- How big is the egg at the start, after one day and at the end?
Ask your child to guess before each test, then compare their guess with the result. Learning to say “I thought… but actually…” is a valuable science habit.
Troubleshooting
- Shell is still there after three days. Pour out the old vinegar and add fresh vinegar. The reaction slows as the vinegar is used up, so new vinegar often helps.
- The egg cracked early. Eggs vary, and a small crack can let vinegar in sooner. Set that jar aside and start a new one.
- A film or foam has formed. That is normal. Rinse the egg gently when you take it out.
- The egg broke when lifted. Use a large spoon and lift it slowly. Fresh eggs can be more fragile than older ones, and that is a good question to explore.
- The jar smells strongly. Vinegar has a sharp smell. Keep the jar in a ventilated spot and out of reach of children who might open it.
Recording the results
A daily drawing, a measurement and a sentence is plenty. Younger children can describe what they see while you write it down. Older children can create a small table: Day 1, Day 2, Day 3, with columns for “What I see” and “What changed”.
If you would like a ready-made place to record this and other kitchen experiments, My Science Lab: Experiment Journal for Kids is a 25-page printable PDF for ages 5 to 9 that includes a Bouncy Egg experiment among its 10 kitchen experiments, with materials lists, step-by-step instructions, observation pages and space to draw and write. It is $4.99.
For other age-based ideas, Science Experiments for Kids by Age is a good next stop.
Clean-up
- Pour used vinegar down the sink with running water.
- Put the shell-less egg in the trash, not down the drain.
- Wash the jar, spoon and tray with warm soapy water.
- Wipe the surface where the egg was handled.
- Wash everyone’s hands thoroughly.
A final thought
The bouncy egg experiment is slow, which is exactly why children remember it. They have to wait, observe and wonder. Even if the bounce is more of a wobble, the egg has taught them something about how materials change.
