What would be an example of a NON controlled variable? ?

study where 1/2 the kids watch edu TV and 1/2 the kids watch cartoons?What would be an example of a NON controlled variable? ?
== In the design of experiments and data analysis, control variables are those variables that are not changed throughout the trials in an experiment because the experimenter is not interested in the effect of that variable being changed for that particular experiment. In other words, control variables are extraneous factors, possibly affecting the experiment, that are kept constant so as to minimize their effects on the outcome. An example of a control variable in an experiment might be keeping the pressure constant in an experiment designed to test the effects of temperature on bacterial growth.