DIY Geode Cake Tutorial: School Holiday Project

DIY Geode Cake Tutorial: School Holiday Project

Here is a perfect indoor, multi-step activity to occupy the little ones, while slipping some hidden science into the mix.

  • Difficulty: Medium (Handling Hot Liquid and Stove Use Required)
  • Time Required: 2-3 weeks (for crystal), 2 hours (for decorating)

Geode cake is popping up all over the Internet, but it is imitating a natural geology phenomenon in the world. Taking the same principle, you can replicate this ancient science in an edible masterpiece.

This cakes take a bit of planning (best started 2-3 weeks ahead) but can be done with most common pantry items and tools. The result is worth the wait.

Growing the Crystals

*****This must be done by an adult. Sugar syrup is extremely hot (hotter than boiling water)! Even adult needs to be careful!*****

We will use the process of “crystallisation” to make our edible crystals.

You need…

  • 2kg of sugar
  • 500g of water
  • Skewers
  • Food dye (optional)

To Make the Crystal…

Put the water and 3/4 of the sugar in a pot. Heat the mixture until the sugar have melted.

Add half a cup of sugar at a time until you can see sugar crystals not melting at the bottom even when you stir.

Add food dye if using and stir

* Be Careful: Very Hot! * Pour sugar syrup into heat resistant containers e.g. glass. Let cool.

Wet the skewers with a little water and shake off the excess. Sprinkle sugar onto damp skewer.

When syrup is cool, put sugared skewer into the sugar syrup without touching any sides or bottom of the jar. If needed, clip some clothes peg on top to help the skewer stay straight.

Cover with paper towel. Wait for crystals to grow….for 2-3 weeks.

Remove skewer with grown crystal from the syrup onto sieves to drain and dry. Bend the skewer to get the crystals off .

If you are not doing the cake immediately, store the dry crystal on some baking paper in an airtight container.

Assembling the Cake

You need….

  • Dense Round Cake of Your Choice (e.g. mud or butter cake)
  • Enough Buttercream to Cover Cake
  • Gold and Black Food Gel Colouring
  • Sugar Crystals You Have Grown
  • Black Powder Food Colouring (optional)

Mix in gold food colouring to your buttercream. Put enough just so its a creamy colour.

Add black food colouring to your buttercream. Mix at low speed for a few seconds – just until its marbled. We are looking for streaks of cream and grey.

Trim the cake top edge so that its round up the top. Don’t worry if its a bit rough, no stones are perfectly round!

Have a look at how many sugar pieces you got. Cut a wedge out of the top of the cake that can be covered with what you have in one layer. (Hint: Start small – you can always carve away more!)

Cover the entire cake with buttercream. Dab the butttercream cream with the tip of spatula to create rock like texture.

Start from the middle of the wedge, push a piece of sugar crystal into the buttercream. Work your way out in concentric circles until you meet the edge of the wedge.

To finish, sparingly sprinkle black food powder colouring on top.

Voila, enjoy and wow people with your edible crystal geode!

Level Up…

If you want to make the geode super realistic, you can grow 2 different colour crystals. Just pour off half of the sugar syrup into one container when boiled. Add more colouring to the remaining syrup in the pot to make it darker. Pour the darker syrup into a separate container with its own sugared skewer. Leave for 2-3 weeks. When placing the crystal onto the cake, start with darker shade in the middle and continue with increasingly lighter crystals on the outside.

How are Geodes Formed?

Geodes starts off as air pockets when rocks are formed. For example, lava running off a volcano may run and cool in such a way that gaps are trapped inside. (Like gaps that gets trapped when making a trifle). Water with lots of mineral gets into those air pockets. When the water contains too much mineral, crystals starts to grow in that air gap. Just like when we put so much sugar in the syrup, the sugar wants to escape onto our skewers. So a few hundred/thousand/million years later when a miner comes along and breaks open that rock, it contains a beautiful crystal inside.

Its National Science Week. Let’s Try Something New (For All Ages)…

Its that time of the year again… National Science Week. If you are like us, a bit time poor to get yourself out to the activities out there, we’ve got a few suggestions to try at home.

Best of all all you need is a computer/mobile device. If you don’t like it, just delete it.

Most of the them are free so there is no excuse!

Kinder – Primary school

Bits Box (Try Mode)

Technically a paid monthly coding subscription activity box. However you can try a handful of apps to see whether your child will like it. To access the try area, click on “Kids Sign In” on the main page. Then “Get Started”. At which point a tablet will come up on screen and there is an option for “Here the First Time?”, click “Let’s Go”. This will then allow you to try 5 apps for free.

Scratch Junior

Developed by a consortium of educational institution (including MIT) and private companies. Its a free app designed for 5-7 year olds in basic block programming. Providing ability to drag and drop commands with its bright attractive colour, it allows kids to start exploring the logic of coding. The good thing is it is supported by lots of community activities, so if you ever get stuck one google search or looking up nearest event will get you up and going again.

Late Primary School – High School


The original children coding teaching tool. It offers block based programming, but also extend these by having ability for advance functions like variables, defining complex logic. Great extension tool once kids get sick of Scratch Junior. Only available online, it does have an offline mode allowing you to work on projects even when there is no internet.

Also have a large community where you can peek inside other people programs. It does require sign up to save your projects, so parental supervision is still advised.


Created by Carnegie Mellon University, Alice is a whole package that teaches older kids how to program in order to produce an animation. This gives 2 sets of skills (programming and animation) in one go. It does require a bit more knowledge to setup, as it provides more options to customise to what you want to use the software for.

However once you setup you can have fun all day long creating life like animation shorts like a pro.

Happy Coding!!!


This is an unpaid post.  We are not associated with Carnegie Mellon University, Alice, Bitsbox, Scratch, Scratch Jr or MIT.

Who Needs Their Right Brain in Science?

Who Needs Their Right Brain in Science?

Science and engineering have always been painted as “logical/left brain centric”, that cannot be performed by “emotional/right brain centric” people. However, a documentary put together by Neuroscientist David Eagleman demonstrates that its more of a team effort then a race between the 2 sides of our brain.

In Episode 4 of “The Brain“, an engineer in a motorbike accident underwent a surgery to cut the connection between left and right half of her brain.

While she improved physically, the long term effect of the surgery was that she cannot make decisions on even the most basic of things. In a grocery store, she struggled to choose between the myriad of products that are the same (e.g. between different type of potatoes).

This is because we make decisions based on which option “feels good” to us. Unconsciously we score options from the “emotional side” of the brain. The “logical” left brain rely on that scoring to finalise a decision.

When that feedback from the right is no longer available to our logical left brain, no decision can be made as all options look exactly as appealing as each other.

In real life, 2 people put in the same dilemma may choose varying options. Different people put different “emotional weights” on the same options based on their individual backgrounds and experiences.

This shows that intuition and gut feel is just as important in a “logical” field like science as the hard nosed facts.

For those after a heavier read (i.e. more information), there is a survey of research from Harvard that summarises the common themes on which people base their decisions on emotionally.


This is an unpaid post. We have no association with Dr David Eagleman, Harvard or PBS.

Easter Bunnies Alert: Handmade Hot Cross Buns Now Available

Easter Bunnies Alert: Handmade Hot Cross Buns Now Available

We are excited to announce the arrival of our hand made Hot Cross Buns in our Etsy store!

  • Made with 95% certified organic ingredients
  • No added preservatives
  • No added colouring
  • No added flavouring

Just like they used to make it.

**NEW – Group Delivery**
Save on postage, help us minimise carbon footprint, and getting you the product fresh.

To get free postage, have your buns hand delivered on specific dates to physical addresses (no PO Boxes) that fall in specific council areas. Just apply the right coupon code to your delivery address council area during checkout.

* City of Melbourne (incl. CBD) – 29th March 2018 (Thursday) (Coupon: GDMelb29Mar)
* City of Knox – 28th March 2018 (Wednesday) (coupon: GDKnox28Mar)
* City of Monash – 28th March 2018 (Wednesday) (Coupon: GDMon28Mar)

Orders close 24 hours prior to delivery date. If you don’t see your council area in the list above, contact us and we will see what we can do!

Please ensure that there are people to sign for delivery, or leave a note at order time where it can be left safe out of the elements.

Group Delivery Terms & Conditions:
– Order will be delivered on the date specified, regardless of the date order is placed. Orders close 24 hours prior to delivery date.
– No PO or mail boxes qualify for this offer. Destination address must be a street address.
– Apartment/office addresses must include a contact number on the day/process to access the apartment safe drop area.
– If nobody is present at address, the product will be left in a place designated by you. Or if no such place has not been identified, at a place at the discretion of the courier. Any damage or loss resulting from such will be at your own risk.
– Any delivery address used for coupons that doesn’t fall within the corresponding council area will have their order cancelled.

Candle: The Mini Wind Generator

At the end of a long hard day working/playing/studying, there is no more satisfying activity then to soak in a hot bath and maybe have a candle or two to relax.

When those wicks are lit, a mini wind storm is being born. Convection is the principle that hotter air always* rises (being less dense) and cooler air always* (being more dense) falls.

This cycle does not stop until the flame is put out.

In Practical (Zelda) Use … Sort of… 🙂

In the video game “The Legend of Zelda: Breath of the Wild”, convection is used to allow a paraglider to go up instead of down.

If an open paraglider strays above an open fire, e.g. grass fire, the glider is caught above the stream of hot air from the fire that wants to go straight up. This in turns push the glider upwards, instead of down with gravity like in other parts of the game.

In fact, a lot of weather patterns in the world is due to difference in the temperature of air. A classic example of the this is storms where cold meets warm air. The ensuring storm is from hot air’s scramble to go up, while the cold air tries to get as low as possible.

Next time when you lay back in the bubble bath, you can take satisfaction at the wind storm that your candles are creating.

* ...except...

The rise and fall of air is actually related to gravity. Without gravity the principle of convection actually do not hold strictly true. NASA has conducted a series of experiments in space in that this law gets messed up where there are next to no gravity.

Source & Disclaimer

This is an unpaid post. We do not have any affliation with Nintendo, NASA or National Candles Association.


Zelda Breath of the Wild: How to Create Updrafts

Candle Science

Wizards, Invisibility Cloaks and Science?

Wizards, Invisibility Cloaks and Science?

As witches and wizards fly around this time of the year, I got to thinking about the genius that is J. K. Rowling in inspiring kids of all ages to read (me included!).

One of my favourite device in the books are the invisibility cloaks. Scientists have actually been having a go at this for ages. To my delight, I recently discovered that a team at University of Rochester have put together a cloaking device that can be made without electronics, by using simple behaviours of light.

What is Light?

Let’s take a step back, and look at what is light. Light is a ball (or a burst) of energy from any source (e.g. sun, computer screens, lamps) that our eyes can see. When our eyes see how the light ball get stopped, we interpret it as an image in our brains (how eyes see images: subject of another post).

The light ball travels from the sun through space in straight line and hit the first solid object that it encounters. 99% of the time this will mean that it gets stopped (much like a person running into a wall). This can be seen as a shadow.

However there are certain substance in our universe that has special properties. Rather than stopping the light ball dead, a mirror reflects the ball like a trampoline. It bounces off the mirror and travel in the new direction – until it meets the next solid surface where it will stop.

And there are lens (like in your glasses) where the light get to pass through but get slingshot around into a slightly different direction. This is like a detour around a traffic accident on a straight highway. Instead of cars travelling in a straight line, the cars curve around until it goes back to the road where it normally goes before hitting our eyes.

So how do invisibility device work then?

Invisibility cloak work by using the principle of bending the light. It uses a set of 4 lenses. As light pass through each lens, the path of the light get slightly altered. Until it creates enough space in the middle that a solid object like a hand can be placed in the middle without stopping the light getting to your eye.

But when you see the image through the lens, it looks like the hand is not in the middle. That is because our eyes are programmed to see anything that enters are eyes as if its straight in front, as it doesn’t know about the bent around path.

Kudos to the team at University of Rochester for using the KISS principle and thinking outside the box.

Kickstarter Update

Thanks to the people who have already backed us!!! There is still some Early Bird rewards available. Get it before you miss out.