Question: Ms. Teridann, a geologist, made a chart showing the scratch-test data for 3 minerals (Mineral X, Mineral Y, and Mineral Z). She wrote "yes" if the tool scratched the mineral and wrote "no" if it did not scratch it. Topaz is a mineral that cannot be scratched by a fingernail, a penny, or a paperclip. How hard is topaz compared to minerals X, Y, and Z? Explain how you know.
Reference answer: Topaz would be the hardest of the 4 minerals because none of the tools could scratch topaz and at least one tool could scratch each of the other minerals.

Student answer: Topaz is harder because it would be all no on the chart.

Student answer: Topaz is harder. Because topaz is the hardest birthstone.

Student answer: Topaz is hard because you cannot scratch it with penny, fingernail or a paperclip.

Student answer: M to Z is harder than mineral X and Y.

Student answer: It is harder than X Y Z because we read about it this morning.

Student answer: It is harder than them.

Student answer: It is harder than minerals X, Y, and Z because it cannot be scratched by either one.

Student answer: A topaz is compared to Z because it cannot be scratched with 2 thirds things. Y is all the opposite of topaz. X cannot be scratched with one third of a topaz cannot be scratched.

Student answer: The Topaz is the first hardest mineral out of the 3 on the chart.

Student answer: Topaz is harder than all of them. It is just barely harder than Z, way harder than Y, and pretty harder than X.

Student answer: Topaz is harder than X, Y, and Z because Topaz cannot be scratched by a fingernail, a penny, or a paperclip so it is the hardest.

Student answer: Tied with mineral Y because they are both yes, yes, and yes.

Student answer: Topaz would be all no's compared the minerals X, Y, and Z because topaz is one of the scratch free minerals.

Student answer: Topaz is harder than minerals X, Y, and Z because Topaz cannot be scratched by a fingernail, penny or a paperclip. So it is harder.

Student answer: It is a soft rock Z, I think it is the same as Y because they can both be scratched by everything. It is little bit hard to X.

Student answer: Topaz is harder than X, Y, and Z because it cannot be scratched by a fingernail, a laser, or a paperclip.

Student answer: Topaz is the hardest out of all minerals because it did not get scratched by any tool.

Student answer: Like steel if you rub them and if it does not scratch.

Student answer: It is harder than all of the other minerals because it cannot get scratched by none of the scratching materials and all the other minerals can get scratched at least one time.

Student answer: It is harder than X, Y, Z. I know it is harder than X, Y, and Z because nothing can scratch it.

Student answer: Minerals X has 2 of them in a paperclip and penny. And the Y, Z and the minerals Y is the hardest in it.

Student answer: It is the hardest because it cannot be scratched by any of them and the others can be scratched with at least one of the minerals.

Student answer: Mineral Z can scratch topaz because mineral Z cannot be scratched by a penny or a fingernail but it can get scratched by a paperclip.

Student answer: It is so strong that minerals X, Y, Z cannot break it.

Student answer: I know because when you break a rock that is when you know it is hard or not hard.

Student answer: How it is compared to X, Y, and Z is that the finger and the penny cannot scratch mineral X and Z.

Student answer: I know it is Z because it has one yes and 2 no's.

Student answer: Mineral Z cannot be scratched by penny, fingernail, and paperclip. Topaz cannot be scratched by anything.

Student answer: Topaz has to have X, Y, Z as minerals.

Student answer: Because it is harder.

Student answer: I know because a fingernail cannot be scratched the most.

Student answer: Topaz is the hardest because none of them can scratch it but at least one them can scratch X, Y, Z.

Student answer: Topaz would be the hardest because none of the tools could scratch it and at least one tool.

Student answer: Topaz would be hardest because none of the tools could scratch it and at least one tool could scratch X Y Z.

Student answer: It would be the hardest because none of the tools could scratch it.

Student answer: Topaz would be hardest because none of the tools could scratch it and at least one tool could scratch X, Y, and Z.