What would be the independent variable in this science experiment?

I'm testing the effectiveness of salt in controlling bacterial growth in milk. I'm going to be using 2 diff brands of milk and different amounts of salt and then counting the number of bacterial colonies (in agar plates). Just wondering, what would be the independent variable in this experiment?

Is it the different amount of salt added?What would be the independent variable in this science experiment?
The independent variable should be the amount of salt added because it affects the dependent variable, that is the amount of bacterial growth in milk. Since the amount of milk is kept constant for the 2 brands, it is a controlled variable.

If the experiment is investigating the number of bacterial colonies for different brands of milk, the independent variable will then be the brand of milk, with the amount of salt used and the amount of milk used kept constant.

Good luck for your experiment! :DWhat would be the independent variable in this science experiment?
well you've got two variables and no control.. so its not going to work.

you are going to need (for example)

20ml X brand milk with no added salt

20ml X brand milk with 1gm salt

20ml X brand milk with 5gm salt

20ml Y brand milk with no added salt

20ml Y brand milk with 1gm salt

20ml Y brand milk with 5gm salt

so each of your two brand types of milk with no added salt are your control. and your variables are your milk brand and also the amount of salt.
alternatively you could just use one type of milk as it seems like the experiment is really based on the salts effectiveness rather than the brand of milk.

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