STES Identifying Variables

Hi, and welcome. Today we're going to discuss identifying variables, something that's absolutely essential to your future career in science. It's a fundamental component of all experimental design. Remember that a variable is any factor that can change in the next experiment. There are three primary kinds of variables. The first that we'll discuss is the independent variable. It is also frequently known as the manipulated variable. This is the factor that is changed by the scientist. It is what he or she wants to test or manipulate. It is what's changed to find out what happens when this item is changed. The next is the dependent variable. It's something that might be affected by the change in the independent variable. It's the outcome of the experiment. What is observed? What is measured? It's the data that's collected during investigation. The dependent variable relies on the independent variable. It depends on it and it changes as a result of the independent variable. The next is known as constants. These are the variables that are not changed in the experiment. They're kept constant or the same throughout the duration of the entire experiment. There are also frequently known as controlled variables because they are those things that the scientists controls throughout the experiment. These are necessary to allow for a fair test or validity in an experiment. Remember that validity means that the results of the experiment can be accepted that they appear truthful and accurate and can be trusted. Is essential for a scientist only change one variable in a controlled experiment so that he or she has validity. The best way to understand these variables is to look at examples. Let's look at a couple of experience now. For example, students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle. Let's identify the variables in this investigation. What was the independent variable? The ages of the students, different ages were tested by the scientist. What was the dependent variable? The time it took to put the puzzle together. The time was observed and measured by the scientist for both age groups. What was a constant? Each age group used the same puzzle. All of the participants were tested with the same jigsaw puzzle. It would not have been fair test if some had an easy 30 piece puzzle, and some had a harder 500 piece puzzle. Another example. An investigation was done with an electromagnetic system made from a battery and a wire wrapped around a nail. Different sizes of nails were used. The number of paper clips the electromagnet could pick up was measured. Let's look at the variables in this investigation. The independent variable was the sizes of the nails. These were changed by the scientist. The dependent variable was the outcome, what happened. Well, a different number of paper clips were picked up. The number of paper clips were observed and counted by the scientist. Constants. The battery, the battery type, the wire type, and the type of nail. We're all kept constant. None of these items were changed throughout the duration of the experiment. But one sole variable that was changed was the size of the nail. Let's look at one more. The higher the temperature of water, the faster an egg will boil. The independent variable is the temperature of the water. It's what the scientist plans on changing. The dependent variable, the time it takes to actually cook the egg. This is what will be measured. Constants, the type of egg used. There are more constants, you can think about the water that's used to boil the egg, the heat source, the type of pan that's used frequently, experiments have a number of constants because you want to maintain control over the experiment for its validity. Let's look at the last one. The temperature of water was measured at different depths of a pond. The independent variable, the depth of the water. Dependent variable, the temperatures. The constant, thermometer, and of course the pond's location. As I stated before, understanding variables is essential to functioning in science. It's the foundation of designing investigations. It will be used throughout your career in science and particularly this year in our experiments and as we venture into the science fair. My recommendation to you is to keep practicing. Look at the samples. Go over them until you can identify the variables. Thanks for joining me today and I hope this presentation will help you.