Science Buddies: "Ask an Expert"

My 4th grade daughter is doing her science fair project on how food coloring moves when dropped into salt water, fresh water and carbonated water. What kind of background information does she need to research?

Thanks!

Hello,
This is an excellent project that explores the concept of density. Therefore, she should research density in general and the average densities for each of these mixtures. While looking at density, she should also look at why things are more dense than others (based on the distance between molecules) and what outside factors affect density to determine her experimental controls. I don't want to say to much as to spoil her experiment, but if you would like me to explain more or have any other questions, please don't hesitate to post in this thread again.

I hope this helps!
Meg