Year 6 have been learning about micro-organisms. Yeast is a microbe that feeds on sugar. When the sugar is digested a gas is released called carbon dioxide. We can see this as bubbles.

How would the amount of sugar added to the yeast affect the size of the balloon?

An idea that needs to be proven is called a hypothesis. We came up with….As the amount of sugar increases, the size of the balloon will increase, because there is more carbon dioxide being released.

How does it work?
As the yeast eats the sugar, it releases a gas called carbon dioxide. The gas fills the bottle and then fills the balloon as more gas is created. We all know that there are “holes” in bread, but how are they made? Most breads are made using YEAST. Believe it or not, yeast is actually living micro-organisms! When bread is made, the yeast becomes spread out in flour. Each bit of yeast makes tiny gas bubbles and that puts millions of bubbles (holes) in our bread before it gets baked. When the bread gets baked in the oven, the yeast dies and leaves all those bubbles (holes) in the bread. Yum!