A cauldron of science!

After a bit of a break as life was too hectic, I've decided to return to blogging about our science and maths-based activities.  My eldest (now 7) is very keen on STEM and my littlest (now 4) hasn't done quite so much as I've been very busy with work the last couple of years.

I'm aiming to revisit some of the things we've done before, but with an audience that's a few years older.  I'm going to keep posting on Instagram but not Twitter (or whatever it's now called), and might manage to put quicker entries on there for things that don't justify a blog post.

For Halloween, I decided to set up a themed science activity.  I hid a plastic spider and a couple of blobs of gel food colouring under some bicarbonate of soda in a plastic cauldron.  

Potion mixing setup

I gave the boys a wand (cocktail stirrer!), pipette and four "potions":

- "Pickling potion", otherwise known as vinegar, to react with the bicarb and produce carbon dioxide.

- "Bubble potion", otherwise known as washing up liquid (detergent), diluted with water.  The idea here is to trap the carbon dioxide in bubbles so the reaction looks more spectacular!

- "Forest potion", some pine needle oil.  This is totally optional, but I'd got it and thought it'd make the whole thing smell a bit nicer!

- "Essence of life", which was a beaker of water.

I wrote a note explaining that they were to practice their potions and see what they could make.  I wanted it to be open-ended so that they could explore and we could talk about what was happening. The small one chose picking potion first, and there was a "wow" as his cauldron fizzed and a spider appeared!  

The big one chose bubble potion first, as he knew that the picking potion was vinegar from the smell and he wanted to see what happened if he added it because that was something he'd not tried before.  It dissolved much of the bicarb, and the spider appeared, but nothing else happened.  He added some vinegar and got better bubbles than his brother!  We discussed how the detergent traps the carbon dioxide that the chemical reaction is making in the bubbles.

Potions in progress

They did lots more experimentation, with the food colouring appearing in their mix eventually (gel colour coated in bicarb doesn't seem to dissolve very easily) and we talked about why I'd called water "essence of life" and how every living creature has water in it.  Eventually we stopped getting more bubbles when they added the vinegar and we talked about how you need the bicarb to react, and it can run out so the vinegar doesn't make any more carbon dioxide.

You can make this as science based as you want with questions about predictions, discussion about chemical reactions and what we need water for or just do as a Halloween activity.  You could also throw in any other "potions" that don't react, or ones that do - like lemon juice - if you wanted to give kids more choice in what they add.