The fact that yeast breathes out carbon dioxide may not be able to convince pupils without conducting an experiment to satisfy their curiosity and to resolve the doubts surrounding them.
The pupils never find it hard to digest all the theories learned as they often have the opportunity to prove what they have learned, especially in Science.
Our Standard 3 pupils managed to conduct an experiment and they looked on in awe when the size of the balloon increased. Finally, it convinced them that yeast breathes out carbon dioxide, hence making the balloon to expand.