Observational study and independent variables

[HAN MOM]

My 10 yr old daughter is doing a project where she has recorded road kill in a 1 mile stretch of park that we drive through on a near daily basis. She has kept a log book of the date, location and the type of animal observed from March 09- Dec 09. SHe wanted to know if there was any reason why sometimes we see more than others, and what is seen more than others. We looked at time of year, moon phases, and temperature. Are these considered the independent variable? Looking at the materials we got from her teacher for the science fair project, we have not done a traditional experiment. We are supposed to list the independent variables. Her teacher has signed off on everything she has done so far, we are putting the board together this weekend. Please help - Right now we have the independent variables as moon phase, temperature and months; the dependent variable is the road kill and the constants is the log of the road kill. Is this right? She must explain all this in her report. And, is it right to call this an Observational Study instead of an Experiment?

[MelissaB]

Yes, this is an observational study instead of an experiment--but you can still learn a lot from an observational study! This sounds like a really interesting project! Did she get any interesting relationships? I would think that temperature might actually be an important variable (though snow cover might be even more important, if you live somewhere where it snows).

You are right about the independent and dependent variables. However, the log book is not a control variable. Control variables are variables which could affect the dependent variable (road kill) but that you kept constant during the experiment. Here's a hint that should point you toward your main control variable: did you look on any other roads during the experiment?

If you would like some help putting together the board, etc., Science Buddies has some great resources for that, on this page: http://sciencebuddies.com/science-fair- ... oard.shtml. You might want to take a look at them.