Experiments and Engineering Activities!!!

Bread Mould

Moulds are microscopic plants. They are not like green plants, which make their own food from light. Moulds actually eat other things. You have probably seen mould many times. It grows on cheese, oranges bread, and other items that can be found in your home.
Try this experiment and make mould grow.

Materials:

Procedure:
Part 1
  • Mix the flour, salt, oil, and water together in the mixing bowl. Mix until it reaches the consistency of bread dough.
  • The mixture will dry very quickly. Keep it in a covered jar or plastic bag when you are not using it.
Part 2
  • Rub your hands in some soil to get them very dirty.
  • Handle the bread and the dough thoroughly.
  • Put the bread and the dough in seperate jars. Screw the lids tightly on the jars. Label them Bread and Dough. Place the jars near a window.
  • After several days observe what has happened in each jar. Mould should be growing on the plain bread, but not on the oil-and-salt dough. Why is this so? What are some ways the bread and dough are different?
dough

What happened?

Mould grew on your bread dough! The bread dough and salt provided food for the mould. Where did the mould come from? Mould spores (like seeds) are everywhere. They are even flying around in the air, but since they are so incredibly small, our eyes can't see them. More mould probably grew on the bread dough with the dirt on it. Why do you think more mould grew on the bread dough with dirt? Dirt acts like glue, and catches mould spores. There were more mould spores on the dirty bread dough than the clean bread dough, so more mould grew on the dirty bread dough.
Why do you think the jars were put by the window? Mould like the warmth. The sun shining through the window probably provided extra warmth for the mould to grow. Mould grows the best at 30oC.
Why did you have to seal the lids on the jar? Mould likes moisture. By closing the lid of the jar, the moisture gets trapped inside the jar providing the perfect environment for the mould to grow.

More?

Look up mould and penicillin in the encyclopedia, a science book, or the internet for some interesting information.
Did you know that mould is used in the cheese-making process? Read about this process and share what you learned at the CAGIS message centre.
Make a list of all the places you have seen mould growing. Remember, some might be indoors and others might be outdoors. What hypotheses can you make about where mould grows best?

Reproduced with permission from 1988 Educational Insights, Kitchen Science, #23.