Halloween is all about being gory, right? Well, what could be more gory than doing brain surgery on your very own Biohazard Brain In A Bag. Let’s get cracking!

What do I need?

• Sandwich bag
• 3 pencils
• Red food colouring
• Pen
• Plate

STEP1 – The first thing to do is to draw your ‘brain’ onto our sandwich bag. It’s almost impossible that you’ll be worse at drawing than me so just take this as a rough idea and make sure yours looks way more awesome!

STEP2 – Fill your sandwich bag with water.

WARNING: Make sure that you do this experiment somewhere where you don’t mind making a bit of a mess. The kitchen might be perfect!

STEP3 – Add some red food colouring to make your brain look even more disgusting.

STEP4 – It’s time to attempt brain surgery on your Biohazard Brain In A Bag!

STEP5 – Carefully push your pencils through your brain in a bag...does it leak? Why not!?!?

What’s going on?

Pretty nerve-wracking putting that first pencil through your brain in a bag wasn’t it? Did you feel sure that your brain in a bag was going to leak everywhere?

How does it work? Well, what happens when you take the pens out? (Best to try this over the sink!)

As soon as you remove the pens you create a space and the water comes out. But with the pens still in there’s no room for the water to squeeze out as the plastic sandwich bag stretches around the pens, forming a tight seal!

More Fun Please! - Experiment like a real scientist!

• Does putting more or less water in your brain in a bag change things?
• What else could you try this experiment with? Apart from pencils?
• Does it make a difference if the top of your sandwich bag is open or closed?