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Hello Chase, In order to test the effects of light on bread mould you need to set up an experiment. There are two things you need to have in your experiment to make it a good experiment:
1. A 'control'.
2. Replicates

1. The 'control'
Obviously in order to test the effects of light on bread mold you will need to actually shine some light on some bread mold and see what happens. This is your 'treatment'.

However, it is vitally important that you know what would have happened without the treatment (in this case added light). Let's pretend that you do a test a you find that the bread mold under the light actually dies. How do you know if your bread mold died because light was added or because at that time of year all bread mold would die naturally or because by adding light you caused the temperature to rise and that killed the bread mold? The answer is that you do not know unless you have taken the trouble to find out with anouther test called the 'control'. The 'control' is a piece of bread mold, identical to the 'treatment' bread mold, which is placed in identical conditions to the 'treatment' piece of bread mold except that light is removed. Your 'control' piece of bread mold will need to be (to the best of your abillity) at the same temperature, in the same area, at similar humidity, etc. Part of the skill of designing a scientific experiment is being able think of all the possible things which might be affecting the bread mold and keeping them the same in both the 'treatment' and the 'control' (except, of course, for the presence of light) so that when you find a difference between the 'treatment' and the 'control' you are sure that it is the result of the light rather than something else.

2. Replication
Imagine you did got a piece of bread mold and shone a light on it...but you had really bad luck and got some sick bread mold that was about to die anyway. You would conclude that light kills bread mold even though the bread mold died bcause it was sick rather than because of the light. If you did the same thing with five bread molds you would have to be pretty unlucky to get five sick bread molds. That is why scientists repeat the experiment to check that the results weren't just because of bad (or good) luck. Both the treatment and the control need to be repeated (replicated).

The experiment
To test whether light effects bread mold I would:
Set up two sets of five boxes.

One set of five boxes would have thick clear plastic on the top (to let inthe light) and would contain pieces of bread with mold.

The other set of five boxes would have thick white plastic on the top (to block the light) and would contain pieces of bread with mold.

I would put the boxes in a well lit room for a week and see what happens. Make sure you don't let the bread and the bread mold dry out.

Good luck.

Cameron Millsom

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