Science Buddies: "Ask an Expert"

[Posted on behalf of a teacher.]

wanted to do goo be gone project with Grade 4s but wanted to half all the materials and omit the ratio part...will we still be able to see results and what criteria then would be a good solvent in terms of how much oil remains?



[Project: https://www.sciencebuddies.org/science- ... p025.shtml]

I wonder why the teacher wants to use half the material? And, why drop calculating the ratios??

Other experts should correct me if I'm wrong/too pessimistic - but I think that using smaller amounts of oil, water, and absorbents will make it more difficult for the students to make their measurements as precisely and the differences in effectiveness between the absorbents won't be as large. And, by using ratios, the effectiveness of the absorbents is being measured "relative" to the remaining amounts of water and oil. The ratio is used as a way to control for the initial amount of water and oil.

It might be helpful if the teacher explained the rationale behind why dropping the use of ratios!