Science Buddies: "Ask an Expert"

We have done the experiment but I'm not sure what caused our out come and how to finish up the project. We soaked 3 radishes in water that was colored blue. We soaked 3 radishes in colored water and added sugar and the same thing for 3 more radishes w/ salt. I'm not sure why the radishes in the plain water soaked up more coloring then the other 2 solutions. The radishes in the plain water also molded faster. When we set out on this adventure we originally started to grow radishes w/ these same solutions to see what osmosis would do. But the salt solution of course didn't allow the radishes to grow at all and the other pots didn't do well either beings that it is winter and they don't grow real well in the house even under a grow light. So I guess I'm totally lost on what to say about this last experiment.

Well, basically what's going on there is that the salt or sugar solution is "hypertonic" (here's a website that illustrates this in a simple way: http://www.biologycorner.com/bio1/diffusion.html). That is causing less water to seep into the radish, carrying less dye in with it. There's a pretty good description of osmosis on Wikipedia (here: http://en.wikipedia.org/wiki/Osmosis), though I caution that you may want to find a more "primary" source to quote because many teachers don't like students to quote wikipedia (or any encyclopedia, for that matter).

Mother,

I think that one of the most important things to realize here is that your child's experiment is note a failure. Science experiments often don't work, and nothing is wrong with that. You haven't failed or ruined your child's project. The most important thing to remember when helping your child with his/her science fair project is to follow the scientific method, which it sounds like you have. It is the process of science that is the most important thing in a science fair project.

Feel free to look for explanations to why the experiment turned out the way it did; Ray Trent posted some very useful sites. But remember that the most important thing is to design and follow a procedure, make observations, and report on what you observed. You've done a wonderful job of helping your child; I hope both of you enjoy finishing the project.

Let us know if we can be of any further help!