Can someone help me with my controlled variable?s?

i have science project due on friday but i dont knkow what they are can someone tell me what they are and how to do it? ASAP PLEASE!Can someone help me with my controlled variable?s?
Describe your project --


controlled variables are any elements that could possibly affect your dependent variable, so you ';control'; them by making sure they are the same across all situations -- the only change you want is from your independent variable





For example, if you are studying the affect of gamma rays on man-in-the-moon marigolds, it is vital that the only difference between your two crops of marigolds is whether or not they receive gamma rays.





So you control the temperature, the lighting, the drafts, the humidity, the amount you talk to each set of flowers....





You can see why scientists believe randomization is an important method for excluding extraneous effects.... there are so many elements to try and control, and we can't be sure we get all of themCan someone help me with my controlled variable?s?
controlled variables are everything you made stay the same throughout the experiment
basically what a controlled variable means is that one variable always stays the same.





for example, if your project is about which car goes down a ramp the fastest, your controlled variable would be the ramp angle, which always stays the same. the variable that changes would be the car that goes down the ramp.





it's important to have a controlled variable so you have the most accurate results. if you changed both the car and the ramp angle every time in the experiment stated above, your results wouldn't be accurate.
A controlled variable is one you do not manipulate. You do not want it to affect your experiment, so you randomly assign ';it'; to conditions. If you think (for example) that the sex of a person will influence your experiment (what you are measuring) you do your experiment with all males or all females....you control it. A controlled variable is one you are not directly interested in, but you think it may influence your results, so you control it's affect.....random assignment, or making it not different in the conditions you are manipulating. (keeping it the same)