Rainbow Fizz Cubes – A Colorful Sensory Science Activity.

Okay but how fun is this?!
We froze little cubes of color and turned them into the most magical fizzing rainbow science experiment.

Lily Loved it!
And honestly… me too 🙂

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This one’s super easy, low-prep, and perfect for toddlers who love a little sensory magic.
We tried it on a warm morning and it kept Lily busy way longer than I expected. Totally worth the (tiny bit of) mess.

Let me walk you through how we made our Rainbow Fizz Cubes — plus a few tips I wish I had known before starting!

Why Is Sensory Play Good for Toddlers?

Sensory play isn’t just fun — it’s really, really good for toddler development.

It helps little ones explore and understand the world around them through touch, sight, sound, and sometimes even smell.

And while they’re pouring, dripping, poking, and squishing, they’re also building important skills.

We’re talking fine motor development, language growth, problem-solving, focus, and emotional regulation… all from a simple, colorful play setup.

It’s honestly kind of amazing. And the best part? They don’t even know it’s “educational.”

Why You’ll Love This Activity

It’s colorful.
It fizzes.
It’s science-y but disguised as play.

And it uses ingredients you probably already have in your kitchen.
Always a win.

Also: it’s low stress. No cutting, gluing, or fancy prep. Just mix, freeze, and play.

Video Tutorial

What You’ll Need

Here’s what we used to make our fizzy rainbow cubes:

• Baking soda
• Water
• Liquid food coloring (the brighter, the better!)
• Ice cube tray
• White vinegar
• A pipette, spoon, or squeeze bottle (to drizzle the vinegar) we used this and this.
• Optional: a few drops of dish soap → for extra foam!

A few sensory favorites we love!

How to Make Rainbow Fizz Cubes

You can make just one color or as many as you like — simply repeat the mix below per color.

✨ For one color:

• 1 tablespoon baking soda
• 1 to 1½ teaspoons water
• A few drops of food coloring

Stir it all together in a small bowl until it has the texture of wet sand. Not too drippy, not too dry. Add a tiny splash more water if needed.

Scoop the colored paste into one slot of your ice cube tray and press it down firmly.

Repeat for each color you want!

Freeze the tray for at least 4–5 hours, or overnight.

Time to Fizz! (The Fun Part)

Once your cubes are frozen, pop them out into a shallow tray or dish.
Now give your toddler a pipette, squeeze bottle, or spoon filled with vinegar…

…and watch the magic happen.

As soon as the vinegar hits the cubes, they start fizzing and bubbling — and the colors spread into swirly rainbow puddles.
Add a few drops of dish soap to your vinegar if you want even more foam. It’s totally optional, but I love the fluffy bubbles it creates!

Lily couldn’t stop adding “just one more drop.”
I mean… same.

FAQ

Can I use baking powder instead of baking soda?
Nope — it doesn’t fizz the same way. Stick to baking soda for this one!

Does it have to be food coloring?
Not necessarily — you could try natural colorings, but they may be more muted. We used a super bright liquid set and loved the results.

Is this safe for toddlers?
This activity is made with kitchen-safe ingredients and is generally considered safe for toddlers to explore with their hands. But just a quick note:

Note: Baking soda is taste-safe but not edible in large amounts.
If your toddler still puts everything in their mouth and tends to swallow rather than just taste, you may want to wait a bit before trying this one — or supervise extra closely.

A small accidental taste isn’t dangerous, but consuming larger amounts of baking soda can cause upset stomach or more serious issues.

Always trust your gut (and your toddler’s habits)!

What if I don’t have a pipette?
Use a small spoon, a straw, or even a travel squeeze bottle. Anything that lets them drip the vinegar slowly will work.

Does it stain?
If you use strong food coloring, I’d recommend doing this in a tray or outside, just in case. But it washed off Lily’s hands and clothes without a problem!

Final Thoughts

This was one of those activities that felt like a tiny bit of effort… for a LOT of reward.
It was colorful, calming, and so fun to watch unfold.

If you try these Rainbow Fizz Cubes, I’d love to know how it goes!
Tag me or send a pic — I always love seeing your little ones in action.

And if you want more toddler-friendly sensory fun like this, I’ve got you covered.

More to come soon.
Until then: go fizz a rainbow 💧🌈

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Last update on 2025-09-27 / Affiliate links / Images from Amazon Product Advertising API