You can only change ONE at a time. That's what makes it controlled. It's the only sure way to know what actually changed the experiment.
make sure everything is the same
All science experiments are performed in a controlled manner which means, there will be a positive control, a negative control and importantly the subject sample(s) who's behavior is not known. The experimental observation must be positive with the positive control sample and negative with the negative control sample, no matter whatever the condition is. Only in this set up the result of a subject (which is the actual unknown experimental sample) would be considered as a faithful result.Any fault or irregularities of the controls will destroy the authenticity of an experiment.
An experiment which can be repeated and will yield the same results. Ex. If x+y=z in the experiement if you try the experiment again you should get the same result "z".
A controlled experiment means that you try to keep all the variables that are involved in the experiment under control apart from the Dependent and the Independent variables to make sure that any results obtained from the experiment have been affected by the independent variable and not some other extraneous variable. It also ensures that the experiment would have high validity. That is, if the experiment has really measured what it was supposed to measure.
that you'll have to do the experiment twice to make completely sure is right
If you want to test your hypothesis with a controlled experiment, you should make sure you have only one variable.
You can only change ONE at a time. That's what makes it controlled. It's the only sure way to know what actually changed the experiment.
Repeat the experiment and make sure it is fair.
what does controlling the variable mean?
make sure everything is the same
Experimental variables need to be controlled because they can cause the experiment to be flawed. Variables can change the experiment, and even if it's not a very big change, it will still make the experiment unreliable. For example, let's say a person is trying to see which laundry detergent is better. They stain four shirts with grass stains, and then apply detergent to each one. The experimental variable in that experiment is the stains; In order for the experiment to be accurate, the person doing the experiment must make sure that they put the same amount of grass stains on each shirt. Otherwise, it would be a very incorrect, inaccurate experiment.
To make an experiment more accurate you would have to repeat the experiment 3-5 more times to make it reliable and also you would do what Liverpool college do and compare the answers with other people in the class, community or teacher.
make sure everything is the same
to make sure its correct
I wasn't there
All science experiments are performed in a controlled manner which means, there will be a positive control, a negative control and importantly the subject sample(s) who's behavior is not known. The experimental observation must be positive with the positive control sample and negative with the negative control sample, no matter whatever the condition is. Only in this set up the result of a subject (which is the actual unknown experimental sample) would be considered as a faithful result.Any fault or irregularities of the controls will destroy the authenticity of an experiment.