Today we did an experiment to see how yeast works.
We put 3 tablespoons of flour and 1 ounce of water into jar 1.
We put 3 tablespoons of flour, 1 ounce of water and one quarter teaspoon of yeast into jar 2.
We put them in the heat of the sun for the day.
When we looked at the jars later in the day we notice the mixture in jar 2 had risen and was full of bubbles.
We concluded that the yeast caused the mixture to rise.