Science Buddies: "Ask an Expert"

Trying to identify IV CV and DV in spinning colors experiment. For each trial, each of the 3 primary colors changes
will either hold constant or drop out of the combination. Read your definitions and could use a bit more guidance.
Will you always have a CV or can you just have IV and DVs?

There's always something that's held constant. If you mix vinegar and baking soda into a volcano, do you use the same amount for each experiment? Do you mix them in the same size cup?

In your experiment, did you change the amount and color of the room light for each trial? Did you have the observer stand up close for one trial and across the room for another? Or did you keep the lighting the same and have the observer watch from the same place? Things that could be critical to the result but that you kept the same are CVs. Does that help?

Yes - that makes sense with respect to the CV. However, in this experiment, each of the colors of primary light will be combined with another color of primary light to create a new color. For instances if you combine 50% blue with 50% green, you should expect to see the color Cyan created. If you combine 50% green with 50% red, you should expect to see the color yellow created. If you combine 50% red with 50% blue, you should expect to see magenta created. If you combine all 3 in equal amounts, you get white light. So, I am trying to determine for each combination what the IV and DV would be.

For example for blue + green = cyan. I would say blue and green are IVs and Cyan is the DV. However, I didn't think you could have more than one IV.
For red + green = yellow, Red and green IVs and yellow is DV. This is the part I am confused about.

You may be overthinking this. You have to choose some percentage of coverage for each of the pie slices on the disc as well as the color of those slices. If you have a disc that's 50% red and 50% green, and you change the red to blue, your IV is the color choice. If you keep the slices red and green but make the red 66% instead of 50%, you've changed the size of the slice. If you change more than one thing at a time it's hard, if not impossible to know what causes any effect you see.

In your example, blue + green = cyan. Was the disc red and green beforehand? If it was 50% red and 50% green and you switched it to 50% blue and 50% green instead, I'd say your color choice was the IV. If the percentage of coverage on the disc changed, maybe that becomes the IV, or if you change the speed of the drill, or the color of the room light, or... In the course of your experiment when you just change one thing, that's the IV. It seems like you're changing the color choices on the wheel. Is everything else the same?

Howard

You are right, I am overthinking it. The trial is below. So seems like the percentage of primary color is the IV, the secondary color created is the DV and the CV is distance observed and the amount of light used in the trial etc. Does this make sense to you?


Red Green Blue Result
50% 50% 0% DV
50% 0% 50% DV
0% 50% 50% DV
33% 33% 33% DV

Thanks for your help, I was thinking about too granularly.

Sounds good. I hope you and your daughter had fun doing it and that she has fun (and does well) at the fair.

Howard