This is one of the most reliable classroom and kitchen-table science experiments, and it introduces real chemistry concepts in a way young children can see and feel.
What you’ll need
- Baking soda
- White vinegar
- A small container or a homemade “volcano” shape (modeling clay or a plastic bottle works well)
- A tray to catch overflow
- Optional: red or orange food coloring for a lava effect
Step-by-step instructions
Step 1: Build the volcano shape
Place a small bottle or cup on a tray and, if desired, build a cone shape around it using modeling clay or crumpled paper and tape.
Step 2: Add the baking soda
Spoon two to three tablespoons of baking soda into the container.
Step 3: Add color (optional)
Mix a few drops of red or orange food coloring into a quarter cup of vinegar for a more dramatic effect.
Step 4: Trigger the reaction
Pour the vinegar into the container with the baking soda and step back to watch the eruption.
Safety notes
- Keep the container open. The reaction produces gas, and a sealed bottle or a cork can pop under pressure.
- Vinegar stings if it gets in the eyes, so have children stand back a little and avoid rubbing their eyes; wash hands afterwards.
- Food coloring can stain clothes, tablecloths and countertops, so work on a tray or outside and keep an apron or old shirt handy.
- The mixture is not for tasting, and small children need an adult within arm’s reach.
Get a bigger, foamier eruption
Add a small squirt of dish soap to the baking soda before you pour in the vinegar. The soap traps the gas in bubbles, so instead of a quick fizz you get thick, slow-moving foam that flows down the sides of the volcano. Pouring the vinegar slowly makes the eruption last longer; pouring it all at once makes it faster and taller.
If it doesn’t work
- Weak fizz: make sure you are using baking soda, not cornstarch or flour, and use enough of it.
- Over in a second: the reaction finishes when one of the two ingredients is used up. Adding more vinegar to the leftover baking soda (or the other way round) gives a second, smaller round.
- Not enough color: food coloring mixes into the vinegar more evenly than into the powder, so add it to the vinegar as in step 3.
Questions that turn it into an experiment
Let your child make one change at a time and compare the results:
- What happens with two tablespoons of baking soda compared with three?
- Does lemon juice, which is also an acid, work as well as vinegar?
- What happens if you add dish soap?
- Which changes make the eruption bigger, faster or longer?
Encourage a quick drawing or a tally of each try. Comparing a few results is what makes this a genuine experiment rather than a one-off demonstration. Younger children (roughly three and up) will enjoy watching and pouring with an adult; older children can measure, predict and record their results.
Clean-up
The leftover foam is just water, sodium acetate and bits of baking soda and vinegar, and it rinses down the sink or wipes away with a damp cloth. Wash the tray and the container with warm soapy water and let children help, since cleaning up is part of doing an experiment properly.
Extending the activity
Ask children to predict what will happen before pouring the vinegar, then compare their prediction to what actually occurred. This turns a fun demonstration into a genuine introduction to the scientific method: predict, observe, and explain.
For more hands-on experiments organized by age, see Science Experiments for Kids by Age, or for other household-item science ideas, see Easy STEM Activities for Kids Using Household Items. STEM and Science Activities for Kids at Home: The Complete Guide ties this together with the rest of the site’s science content.
