Science Buddies: "Ask an Expert"

I am helping my daughter who is in 4th grade do a rock candy project for the science fair. She is growing one crystal using a string that we seeded by soaking it in water for five minutes, soaking the excess water out, rolling it in sugar and letting dry overnight. The other string was not seeded. My understanding from this project is that the seeded string should grow the bigger crystals. However, after the first 24 hours of growth, this is definitely not the case. The un-seeded string is much larger than the seeded string. I'm afraid maybe I made a mistake when I made the solution? Both strings are from the same yarn, are the same length, use the same weights and sticks to suspend them from the jars. They also used the same solution and the same size and shape of jars (wide mouth mason jars). Has anyone else ran into this? Should we re-start this project? It is due November 1st so we still have some time left.

I did a little research and it appears that you are doing everything correctly. Thanks for the level of detail in you submission by the way, it helps give us a better understanding of the issue. After reading your post my gut reaction was that you mixed up the strings. After all based on your description they are identical. An easy mistake. I would advise to cut two new pieces of yarn and start again. You haven't lost that much time and as you said you have plenty of time left. This time label the two different pieces clearly, maybe even use two different colors of yarn so you know which is which.

On the other hand, I would also leave the orignal experiment alone. See if any changes occur over time. I read this site: http://chemistry.about.com/od/growingcr ... rystal.htm
and it didn't really explain the rate of growth of seed vs. non-seed, it just mentioned that the seeded string should get bigger eventually. Maybe in the orginal experiment you'll see a slow start for the seeded yarn but eventually the seeded yarn will catch up and out grow the non seeded yarn?

Let me know how it turns out.

-Jason

Thanks. I think we will try again and leave the original expiriment growing. I don't think it's a case of mixing them up. I failed to mention that I marked the stick the seeded string was on before I put it in the solution and did the un-seeded string last. However, I guess this COULD still have happened. I will keep you updated on how it pans out. You would think I could manage a 4th grade level science experiment, ha ha. Guess this is why I am not a scientist. Obviously I am not smarter than a 4th grader. Thank you for your help.

A good reminder to always have more than one trial for any experiment. You should have had a few jars of each type of string.

Your unexpected results could be for any number of things that weren't quite controlled (the strength of the solution, temperature, light, cleanliness of the jars, etc.)

hi guys can i know how to make these good candy