Science Buddies: "Ask an Expert"

Do sugar crystals grow faster in tap water or distilled water? this is the science project that my daughter has to do and we have no idea what to use as variables for that.

Good evening!

Happy to help with this great project! The type of water would actually not make a difference when it boils down to it (pun not intended). You might initially see a quicker crystal showing in the tap water though due to something called condensation nuclei. For this experiment however, let's not worry about that complicated word and narrow it down to "sugar crystals need something to grab onto initially, and tap water has impurities/minerals that allow that to happen quicker than in distilled water". In the end it is the SUGAR and the exactness of sugar weight to water weight that matters.

Did the teacher set out that this experiment was specifically for "different types of water"? If that is the specific experiment being conducted, then my money is on the aforementioned tap water. Honestly, the growth rate will have a lot to do with the water itself. I know that here in California where I live we have "hard water", which means there are a lot of minerals in it. This could be the case where you are too perhaps?

You variables would be "the amount of sugar used" and perhaps even "air exposure" (if part of your experiment involves covering one so not as much air gets in--or different types of jars are used)

Hope this helps, and have fun!! Please feel free to write back if any other questions come up!

Elizabeth

Hello. Along with the great advice you have already received, I would like for your daughter take a first attempt at your variables. First let's review definitions of different types of variables. More discussion can be found here:
https://www.sciencebuddies.org/science- ... bles.shtml

Controlled variable: settings you wish to keep constant in your experiment so that it doesn't affect the outcome
Independent variable: settings which you, as the scientist, change in order to see how it affects the outcome of your experiment
Dependent variable: what you measure to determine whether it is affected by your independent variable(s)

Based on these definitions, what do you think your variables are? Take a crack at it and write back with what you think.

Good luck!
Deana

Thank you very much yours answers helped me a lot; we have more to do for next week, so I will be asking you more questions.

Thanks,
Amyarlene04

Sure thing. Feel free when you have more questions to let us know.

Good luck, and have fun!

Elizabeth

Hello we almost done with the project, the thing is now she has to do a graph with the result but we don't know
what information to use in the graph; what do you think should be my graph information?
(type of water, amount of sugar, amount of water)
I have no idea.

Thank you,
Amyarlene

Hello Amyarlene,

It seems like you've done a good experiment and are in the home stretch. It's exciting to see that you looked at different variables and are now working on how to interpret them. Since you used three different variables, you need to make three different graphs. Think of them as three different questions
1) Does the type of water affect crystal growth?
2) Does the amount of sugar affect crystal growth?
3) Does the amount of water affect crystal growth?

After you make the graphs, it may be clear that one or more variables do or do not affect crystal growth more than the others. Then you can use the graphs to demonstrate this.

Good Luck!
Lynn