O is for Oobleck!

When the sound of the week is "O" (Long and short) you just have to make Oobleck for Discovery time!

 Oobleck is a funny substance. It is runny when you move your hands through it slowly, but goes quite solid when you speed things up.

 The Science behind it… Cornflour is made up of lots of tiny starch particles, these are very attracted to water so the water gets in amongst them very quickly. The water acts as a lubricant, so when you move it slowly the particles have time to move past each other and they can flow like a liquid.

 However if you apply a rapid force it causes the particles to move slightly causing the particles that are almost touching to jam together. And the water that was between them moves sideways slightly into the gaps. Now instead of having lots of lubricated individual particles you have a solid structure of lumps touching each other which can't flow.

Recipe:

You Need:

1 bowl (or tray)

Cornflour

Water

Food colouring

What to do:

1.    Mix 1 part water with 1.5 to 2 parts Cornflour. You may wish to start with one cup of water and one and a half cups of Cornflour, then work in more Cornflour if you want a more 'solid' oobleck. It will take about 10 minutes of mixing to get nice homogeneous oobleck.

2.    Mix in a few drops of food colouring if you want coloured oobleck