Chemical Changes with Yeast

In grade 4 we have observed some different chemical changes using yeast. The first was elephant toothpaste. There is an enzyme in yeast that breaks down hydrogen peroxide into water and oxygen gas. We added some dish soap to trap the gas. The results were pretty cool. You could even try this at home. 

https://www.stevespanglerscience.com/lab/experiments/elephants-toothpaste/

Hydrogen peroxide is available at pharmacies as väteperoxid. A 3% solution works. In this experiment we were able to not only see a chemical change but feel it in the heat that was released. 

Another experiment we did with yeast was comparing what conditions yeast can grow under. We tested different temperatures and also tried giving the yeast sugar. I am impressed by the students' ability to work together in different groups. 

It's important to record and reflect. 

The same test tubes with 20 minutes difference. Tube 2 had yeast in room temperature with sugar solution. Tube 1 was the same temperature but with no sugar. #3 and 4 were very hot and very cold water. 

Learning goals: 
2.28 Know that some changes in materials are reversible and others are irreversible 
2.29 Know about the changes that occur when materials are mixed