Enjoy simple chemistry in the bath tub with these fun LEGO fizzing bath bombs you can make easily with the kids. Explore a cool chemical reaction between an acid and base while you get clean! We love easy science activities for kids!


Surprise Bath Balls

Kids will have awesome clean fun with these scented bath bombs with a surprise LEGO mini-figure inside. Plus, they are just as fun for kids to make as they are to use in the bath!

This homemade bath bomb recipe is definitely more kid friendly then store bought versions which may contain many artificial ingredients. It also avoids fake fragrances, artificial colorings, and glitter.

The bath tub is the perfect place for toddlers and older kids to get creative with homemade kids paints, soap or bath bombs. Also make your own glow in the dark bath paint or LEGO soap! Christmas bath bombs and Halloween bath bombs are fun alternatives!

Easy Science Experiments For Kids At Home

Science learning starts early, and you can be a part of that with setting up science at home with everyday materials. Or you can bring easy science experiments to a group of kids in the classroom!

We find a ton of value in cheap science activities and experiments. All our science experiments use inexpensive, everyday materials you can find at home or source from your local dollar store.

We even have a whole list of kitchen science experiments, using basic supplies you will have in your kitchen.

You can set up your science experiments as an activity focusing on exploration and discovery. Make sure to ask kids questions at each step, discuss what is happening and talk about the science behind it.

Alternatively, you can introduce the scientific method, get kids to record their observations, and make conclusions. Read more about the scientific method for kids to help you get started.

Science Experiments By Age Group

We’ve put together a few separate resources for different age groups, but remember that many experiments will cross over and can be re-tried at several different age levels.

Younger kiddos can enjoy the simplicity and hands-on fun. At the same time, you can talk back and forth about what is happening.

As kiddos get older, they can bring more complexity to the experiments, including using the scientific method, developing hypotheses, exploring variables, creating different tests, and writing conclusions from analyzing data.


Why Do Bath Bombs Fizz?

The best part of bath bombs is of course, the fizzing action which is actually a chemical reaction. Chemistry in the bath tub!

Bath bombs fizz when water triggers a reaction between an acid (citric acid) and a base (baking soda). Usually we see this in one of our volcano experiments, like our LEGO volcano.

This bath bomb is made with citric acid, as found in citrus fruits. It’s also made with sodium bicarbonate or baking soda, which is a base.

The reaction causes the fizziness you can see and hear because the acid and the base combine to create a gas called carbon dioxide. Learn more about acids and bases.

Fun fact, the cornstarch helps to slow down the chemical reaction! This reaction also helps break apart the bath bomb to release any hidden treasures and fragrances you have added.

Fun in the tub! Check out the video.

Click here to get your FREE printable LEGO activities calendar!

How To Make LEGO Bath Bombs


  • 1 cup baking soda
  • ½  cup citric acid
  • ½  cup epsom salts
  • ½ cup cornstarch
  • 2 tsp. coconut oil
  • mica powder for color
  • LEGO mini figures
  • Bath bomb mold
  • Spray bottle with water
  • Optional – Essential oil


STEP 1. Combine all of the dry ingredients.


STEP 2. Next, add your choice of essential oil to the scent strength you like, start with 12 drops. Lavender is a great choice for a relaxing bedtime soak.

For a little one with the sniffles you might add eucalyptus. Need to wake them up in the morning any  citrus essential oil will do just that!


STEP 3. Slowly wet your mixture and mix with your hands, just a spritz of water at a time just until you are able to squeeze it and it maintains its shape, any wetter and the fizzing reaction will go off too soon!

STEP 4. Place a min fig in the bottom of one half of the mold, add mixture and pack tightly, keep packing until each half is overfilled, press them together firmly.


STEP 5. Let your bath bombs dry for several hours until completely hardened. I usually let them sit overnight. Then carefully remove the bath bomb from the mold and keep dry until ready to use.


More Fun Things To Make With LEGO

Printable Science Projects For Kids

If you’re looking to grab all of the printable science projects in one convenient place plus exclusive worksheets, our Science Project Pack is what you need!