Under the Sea

In Year 6 we have been learning about Micro-organisms, which are microscopic living things that you can’t see with the human eye.  You need to use a microscope to see them but they are found absolutely everywhere. Some of them, like yeast are helpful but some of them are harmful and disease causing, like bacteria. We have learnt that every living thing needs 7 things to stay alive and we remember this by using MRS NERG (movement, respiration, sensitivity, nutrition, excretion, reproduction and growth).  By knowing this, we are able to help avoid the spread of bad micro-organisms by making sure we don’t give these tiny living things what they need to stay alive.  To test Mrs Hudson’s theory that micro-organisms grow best when they have food and warmth, we investigated the growth rate and process of yeast.  We set up an experiment with four conical flasks.  One had just yeast, one had yeast and sugar, one had yeast and warm water and the final one had yeast, sugar and warm water.  We kept the test fair by keeping these factors the same: size and shape of flask, same teaspoon to measure, same amount of yeast, same amount of sugar, same amount of water, same temperature of the water.  The factor we changed was what was inside the flask with the yeast.  As soon as we had put the ingredients into each flask, we put a balloon on top so that we could see if the mixture was growing at all.  To our absolute amazement (and excitement!) we found that the yeast, sugar and water mixture very quickly started to react and produce a gas which inflated the balloon.  In fact, the mixture reacted so well that after 30 minutes, the yeast foam was actually rising up into the balloon.  We had fun doing this – it really had a ‘WOW’ Factor.

After 10 minutes.