Sinister Cleans Up – DIY Terrarium

Sinister is starting off his school year by creating his own world to command and conquer.

I like this teacher already.

Sinister is in Year 5 OC (Opportunity Class – like a Gifted program in the public school system). In Science they are studying Space – Significant astronomers; Creation of the Golden Record; How to Survive in Alien Environments (biospheres).

As part of his assignment, Sinister has chosen to develop his own terrarium, focussing on the creation of a self-sustaining environment.

It’s a huge project but he is already noticing how to break it up into smaller scientific components.

For example: we bought a demijohn glass jar on eBay for $20 to house his terrarium (with cork plug). However, it needed a clean.

After a bit of research, Sinister came up with the following:

Hypothesis: That we can clean the demijohn with vinegar and uncooked rice; that the vinegar would wash and disinfect the jar without leaving a heavy chemical residue; that the rice would lightly scrub the jar without scratching.


  1. Pour about a litre of plain white vinegar into the large demijohn.  
  2. Add about a cup of uncooked rice  
  3. Put in the cork and shake it like a Polaroid picture… Well, make sure you use two hands; it’s heavy!!
  4. Empty out the vinegar and rice
  5. Rinse out with copious amounts of water.



Damn thing pretty much glistens. This mini-experiment produced the exact results he was looking for.
Next week: Sinister figures out how to fill and build the soil layers for his terrarium. That’s a tight neck there on the demijohn … But he has a plan!

Forensic Friday #8 – Density Matters

A couple of days ago, Nefarious had lined up Zaltu’s Batman toys.

“Originally, I had them lined up in size. But then this one was smaller but heavier. So I thought to go with something different and do them by weight instead.”

Great opportunity for a lesson in density. Not only will the spawnlings understand a basic scientific concept, but it will help them understanding other minions in the world – like politicians.

Today’s Forensic Friday is a man down; Sinister abandoned us for a day of Minecraft looting with a friend. So let’s make it 6yo (first grade) friendly.

What is Density?

Density is a measurement of how solid something is. If you have two objects of the same size, the more dense object will weigh more than the less dense object. This is because of two things:

  1. The mass of the atoms that make up the object;
  2. The amount of space the object takes up. If the atoms are packed in tightly, it will be denser. I used the example of a ‘dense forest’ and whether you could move easily between the trees. Another example you could use is whether that particular minion has enough space in their brain for ‘free thought’ to flow through – or if they are ‘dense’. We’ve had a few examples of this recently, but I didn’t want to distract Nefarious too much.

The next step to take is to look at the relationship between density and buoyancy. We’re going to come back to this when Sinister comes home because he is really into Marine Biology and this is a core concept to remember when diving. Basically, a less dense substance will float on a more dense substance. A good experiment is the Layer Effect:

Ingredients / Photo by Evil Genius Mum

Ingredients / Photo by Evil Genius Mum

What You Will Need:

  • Oil
  • Water
  • Honey or Golden Syrup (Honey is better to see through, but we were out of honey today)
  • Cork or Styrofoam
  • Grape or Blueberry or Strawberry or something similar
  • Small coin
  • Clear bottle

What You Do:

  1. Fill your bottle one third with honey;
  2. Pour the next third full with oil
  3. Fill the remaining third with water. Allow the liquids to settle before the next step.

    Pouring the Liquids / Photo by Evil Genius Mum

    Pouring the Liquids / Photo by Evil Genius Mum

  4. Take a minute to explain to your spawnlings about the separation of liquids here. Honey/Golden Syrup is really dense, so it will sink to the bottom. Water is not as dense as the syrup but it is definitely more so than the oil. Fortunately, oil and water don’t mix, so they will separate with the oil resting lightly on top.
  5. Let’s just stop for a moment and do a bit of hypothesising. Science ain’t science without a hypothesis, a method, and a written report afterwards. Otherwise, it’s just messing around with stuff. Ask your spawnlings what they think will happen to the next three items: the coin; the fruit; the styrofoam or cork.
  6. Now, drop the coin in the bottle. The coin will drop all the way to the bottom, even through the honey. Thank you, my dense little 10c and 5c pieces.
  7. Next drop the grape or blueberry in (blueberry for us – Zaltu was pigging out on the grapes while Nefarious and I set up the experiment). This one should rest somewhere around the middle.
  8. Finally, the cork or styrofoam. Being REALLY LIGHT, it should rest easily on the top.
Liquid Density / Photo by Evil Genius Mum

Liquid Density / Photo by Evil Genius Mum

And there you go folks! A lovely little lesson in density. When Sinister and EG Dad come home, we might take it the next step and look at buoyancy from a scuba diving point of view. Since I’m asthmatic, I have never been diving so wouldn’t know WTH I’d be talking about. 😛

My Budding Scientists / Photo by Evil Genius Mum

My Budding Scientists / Photo by Evil Genius Mum

Forensic Friday #2 – Slime

“I’ve been slimed!!”

Today’s Forensic Friday experiment is brought to you by the letter S – for SLIME. Ooey, gooey, slime.

Of course Sinister and Nefarious want to make their own slime. And it is a good lesson in chemical reactions (as is any cooking in the house)… My concern is what kind of weaponry they are mentally designing with this new knowledge.

Want to know how to make it yourself? It’s really quite simple, and a great starting point for testing out the ‘evil genius’ of your own spawnlings:

Making Slime

Step 1: In a container, mix together one tablespoon of glue (general craft glue), one tablespoon of water, and one drop of food colouring (Sinister chose BLUE).

Step 2 – In a separate container, dissolve one teaspoon of borax powder in one tablespoon of warm water. Borax powder is POISONOUS – wash your hands after touching it or your slime!

Step 3 – Pour the Borax solution into the glue mixture. Mix with your fingers and a slime should form, almost instantly. It will feel plastic-y and gooey. And awesome.

Step 4 – The glue and the borax mix together to make a new chemical – SLIME!! The borax stops the glue flowing like a liquid. This makes the slime very elastic.

Step 5 – Store your slime in an airtight container.

And there you go! This slime is excellent. We had some extra moisture, but once you squeeze that out it becomes a little sticky and very much like malleable plastic.

Even better: Stretch it at just the right angle, and you can slingshot it right into your kids’ hair.

So I’ve been told 😉