Grow a Crystal Rainbow – St. Patrick’s Day STEM

St. Patrick’s Day is coming up fast and to help celebrate the arrival of little leprechaun’s everywhere I challenged the boys to build a display using some math, science and engineering. St. Patrick’s Day STEM – Build a Leprechaun House with Crystal Rainbow.

St. Patrick’s Day STEM / STEAM Activity

St. Patrick's Day STEM/STEAM Activity that includes math, engineering, science and arts. A great STEM and STEAM activity for young scientists

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St. Patrick’s Day is such a fun holiday. I think one of the reasons I love it is because it signals the waning of winter and the slow, but definite, arrival of spring. This year our winter was very mild, but I still welcome the end of the snow and cold and the arrival of some nice weather so we can get outside and really enjoy the outdoors again!

To celebrate the upcoming St. Patrick’s Day I wanted the kids to design a little display using their engineering and science skills.

Last Halloween we made crystal decorations and then again at Christmas we made a crystal wreath. So for this project it was decided that we should do a crystal rainbow.

NOTE: Since we are using Borax and a stove top with hot water, a responsible adult should do all the steps involving making the solution. Always use proper precautions and safety steps.

How To Make A Crystal Rainbow

The longest part of this project is making the crystal rainbow. So let’s start with that step.


Pipe Cleaners or Chenille Sticks in all the colours of the rainbow
Chopstick or pencil
Warm Water
Large Heat Proof Container or Jar (large enough to hold the pipecleaners)

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Arrange the pipe cleaners in the proper rainbow sequence. Red, Orange, Yellow, Green, Blue, Indigo, Violet. Twist the ends together and tie with a string to hold them together. Leave a little extra string so you can hang the bundle.

Heat enough water on your stove top to fill your jar. Measure your water. Bring it just to a simmer.

For every cup of water add 3 tablespoons of Borax. For our jar we needed 7 cups of water and 21 tbsp of Borax. This is a great moment to get your kids to do the math. Stir to dissolve. Turn off the heat.

Carefully pour the warm water into the jar or container. You can also skip removing the warm water into the container and instead leave it in your pot for this next step.

Place your pipe cleaner bundle into the solution. Ensure it doesn’t touch the sides. Do this by placing a chopstick across the top and tying the bundle to the chopstick so it hangs.

Let sit for 24 hours. Once finished carefully remove it from the jar and place it on a tea towel to dry for a few minutes.

The Crystal Rainbow is done!

St. Patrick's Day STEM/STEAM Activity that includes some math, engineering, science and arts. A great STEM and STEAM activity for young scientists

The colours turned out amazing!

Make Even Bigger Crystals!

Want to grow those crystals even bigger? We learned all the tricks on how to grow really big crystals with this crystal growing experiment. Hint: It’s all about heat!

The secret to growing really big crystals

Engineering a Leprechaun House

For this next step you can use any crafting materials you have around the house. Lego also makes a great tool for building a Leprechaun house.

I let the kids dig through our Tinker Space to see what they wanted to use in their St. Patrick’s Day creation.

They found an empty cornstarch container that was a great gold/yellow colour. They decided it would make a fantastic leprechaun house. We had the beginnings of our project!

Bringing in a bit of math

Using a ruler they measured out the crafting sticks to make the door. Then they made the hat/roof. To do this they used a protractor from their math set to measure and draw the circle for the brim of the hat. I love introducing my kids to math tools in such a fun and non-threatening way.

St. Patrick's Day STEM/STEAM Activity that includes math, engineering, science and arts. A great STEM and STEAM activity for young scientists

The kids decided the rainbow had to land on a pile of gold and treasure! Using some chocolate gold coins and green leprechaun coins they created a pattern for their pile of treasure: 1 gold coin, 3 green coins, 1 gold coin, 3 green coins. Then they finished the top and bottom with an extra gold coin.

Putting it all together

It took a little engineering to get the rainbow to fit nicely and stay in place (the crystal rainbow is quite heavy), but with a few containers placed inside the house they got everything to fit together.

To finish things off they sprinkled our display with some shamrocks.

I think they did a great job and now we have a fancy new seasonal display.

The best part about these open ended projects is that the kids can use their imaginations and come up with the most incredible creations. It’s all a little big of magic when kids light up as they create, grow and learn. This is a great project for capturing that magical love of learning!

More St. Patrick’s Day Fun

Delicious green and gold cheesecake fudge recipe
Pot of Gold Cauldron Bath Bombs
St. Patrick's Day Slime and play time