Science Buddies: "Ask an Expert"

I am doing a fair project asking the question. Is there different amounts of salinity in the bodies of water around Tampa Bay. I have three sample groups. Tampa Bay, the intracoastal and the Gulf of Mexico. When I listed my manipulated variable as the different bodies of water the teacher says I need more. Not sure what else to put. Everything else is the same. I am in 5th grade

Well, I can't speak for your teacher, but I'll give my opinion.

I'm assuming that the manipulated variable is the variable you are changing. (sometimes this variable is called the independent variable.) Since you are measuring how salinity varies in different locations, I would say your manipulated variable is the geographic location of the body of water.

Does she mean more samples of the same manipulated variable?

In other words, should you run down to the Cross Bayou and get a sample, Fort DeSoto Park, Safety Harbor, and Ben T Davis Beach? Or get samples from the Gandy Bridge, Weedon Island, and the Courtney Campbell Causeway??? Or from the fishing pier at the old Sunshine Skyway bridge???