Physical Property: Strength

The strength of a material is its ability to withstand an applied stress without damage. Strength refers to the point which the material begins damage or break from a force applied to it and the damage cannot be reversed when the force is removed. The applied force may be from pulling, pushing, or twisting.

Physical Property: Hardness

Hardness refers to various properties of solid materials that have high resistance to various kinds of permanent shape change when a force, such as hitting or pulling, is applied. In science, there are three main types of hardness:

• Scratch hardness: Resistance to changes on the surface, like scratches, due to friction from a sharp object;
• Indentation hardness: Resistance to changes due to pressure from a sharp object;

• Rebound hardness: Can an object bounce off the material when dropped on it.

Physical Property: Malleability and Ductility

Malleability refers to a material's ability to deform under compressive stress; this is often characterized by the material's ability to form a thin sheet by hammering or rolling.

Ductility refers to a material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire.

Properties of materials (matter).

Bread Mould Experiment with Crazy Chris!

Fungi growth - The Private Life of Fungi

Bread Mold Speed Frame

Bread Mold Hyphae

Why does Bread Mold?

We’ve all seen it. You stick a loaf of bread in your breadbox or pantry, and a few days later you begin to notice blue, green and black fuzz growing on top of it. Bread mold is a common problem, and can actually be the source of many interesting science experiments. But why is a loaf of bread such a desirable source for mold? The answer lies in an understanding of exactly what mold is, where it is found and how it survives.

What is Mold?

Mold is a member of the fungi kingdom, which is a separate categorization from plants and animals. Mushrooms also fall into this category. Fungi can be defined as a plant without chlorophyll, so it cannot get energy directly from the sun. This means that fungi must use other plants and animals as its food source. This is why bread mold is so common – because of the ingredients in bread, it is an excellent source of nutrition for many molds to grow and thrive. It also contains limited moisture content, which is why mold can grow so well instead of bacteria or yeast that requires higher moisture levels to survive.

Bread and Mold Meet

Bread and mold often meet through the mold spores that are in the air. Although you cannot see them, there are probably millions in the air around you. These spores can accumulate in the dust around our home, which is kicked up through cleaning or even someone walking by. The spores can then settle on your bread and the bread molding process will begin. Mold will not only live and feed on bread, it will also reproduce there. This is why you see bread mold spread throughout your loaf if you let it sit there long enough. Mold reproduces as long as it has a nutrient source – sometimes it can double in size in an hour’s time.

Growing your Own Bread Mold

Growing bread mold is not hard to do. You can use a slice of bread that has been rubbed along the floor or other dusty surface, and give it a couple of squirts of water from a spray bottle to moisten it. Place the bread in a sealed bag and leave it in a dark place for a few days. You will find that you are able to grow your own bread mold garden with relative ease and in a fairly short period of time. It’s a great way to bring science into your home!

The Bread Mold Experiment

The aim of the bread mold experiment is to see what organisms are living on the kitchen bench and compare this to what is picked up from just the air alone.

Materials Needed:

·     You will need the following:

·     2 slices of bread (wholemeal is best)

·     cling wrap or sealing sandwich bags

·     spray bottle filled with water

·     magnifying glass (optional)

Procedure:

Step 1: Wipe one of the two slices of bread on the kitchen bench or any other surface regularly used for food preparation. The second slice acts as a control for the first; it shows what would happen without wiping it on the surface.

Step 2: Spray both slices very lightly with water

Step 3: Seal the slices in separate pieces of cling wrap or separate sandwich bags.

Step 4: Place the wrapped bread slices somewhere warm and wait for the mold to grow. Once the difference between the two slices is significant enough, remove them and inspect the results.

Step 5: Examine the mold colonies with a magnifying glass. Note that caution must be taken not to breathe in the dust from the mold colonies as it can cause medical complications.

What is Happening?

The mold colonies have ended up on the bread either from landing on the bread from the air, or as a result of being collected from the bench in the process of wiping. The difference in the quantity and types of mold present show that wiping the bread on the bench results in far greater mold growth as well as diversity.

Possible Extension: Activity to Test Disinfectants

This bread mold experiment can be extended to test different brands of disinfectants. Select up to four different brands of disinfectants you have at home. Example, Dettol, Lysol, bleach, etc.

Treat four pieces of bread, each with a different brand and leave them in the open. Record your observations.

Opening Entry

This blog is for Science Learning.