Formative assessment personalities

What is your interpretation of the phrase “bigger eruption”? I’m just wondering if they’re getting hung up on that. And do you have it purposely written so that there can be both physical and chemical answers given? Or is that just a surprising result? If you do want only answers based on chemical change then you’d have to write that to be specific.

I was looking for things like using the stronger acid and a stronger base, or a limiting reactant, moles and mole ratios and limiting reagents and gas laws and things like that. There were things I was looking for, but that doesn’t necessarily mean that something that wasn’t there was wrong or out of bounds. I would love if they had also included pictures or illustrations. Like, with their answers. With things like when Reinaldo said he’d use hydrochloric acid and sodium hydroxide because they contain hydrogen. I would love to know what that looks like to him.

I mostly was just interested in what they had to say and if it made common sense to me, and if they defended their thinking. But I think they were pretty vague on some things, they didn’t explain fully, they weren’t explaining why, particularly in quantitative terms. I also didn’t see much of a discussion of carbon dioxide.

Sonia talked about collisions, how they are making more product, so it comes out at a greater force. So you think about force being like the amount of gas being shoved out of the test tube. It would, in my understanding of the physics of it, come  out with more force if there is more gas in the same space.

There’s only one student, Albert, who is grossly misunderstanding what’s going on. He is only saying the reactants. Of course misunderstandings are something I’m always looking for, I mean, they are misconceptions. Reinaldo had a lot of misconceptions about chemistry, like if there’s hydrogen in the reactants, it doesn’t create hydrogen gas in the products. If I were to grade it, I’d say Sonia is the best.

There is this confusion that Reinaldo has about a reaction with carbon dioxide, and that comes up with another student too. He thinks we don’t want the gas, right? We can’t even see it, so what’s the point? He does not realize that it’s the gas that drives the foaming.

I would put Sonia’s answers on the board. I think with an assessment,  we are trying to show the students what we are looking for, and I thought this person had very specific answers, ‘I would change this and this is why it would make the reaction bigger’. Seeing an ‘A’ answer, pick the best one, seems to be better than when I tell them what I would have said.

The interesting issue here is helping the kids select the principles that help explain what is happening here. In science, many times we kind of teach a lesson and then give a kid a problem, but the principle they need to apply is the one we taught them just the day before, right? But what if, of those principles, which is the one that applies? Maybe I would give the kids several scientific principles, maybe all the ones here, make them think a little bit more about which ones apply to this problem. So the idea about the volume applies to the gases.