Understanding controlled experiments.

What is science and how does it work? Science is our knowledge of the nature world and the process on how knowledge is built. Science relies on testing of ideas with evidence gathered from the world. Science can't actually be defined, but it can be described as a set of key characteristics.  A Controlled Experiment is an experiment that uses controls and usually separates subjects into one or more control groups. An Independent Variable is a variable that is changed to observe the fact on the dependent variable. A Dependent Variable is a variable that is expected to change when the independent variable changes. A control group is very similar to a controlled experiment. A Placebo is a pill, liquid or powder that has no treatment value. Experimental treatments are usually compared with placebos. A double- blind trial is to investigate efficiency and safety. I understand what a controlled experiment is now, more than i did before because i went through and read all of the different websites that you told us about.