# Issue with using ans_0 for correctness checking

I made this activity: Unit 6, CYU #3: Solving Equations • Activity Builder by Desmos

In it, students solve equations in the graphing calculator component. They put their answer in line 2. I have a hidden folder with a conditional that checks if ans_1 is equal to the intended solution. I use that to set the correct sink.

In the CL, there is a warning that appears, saying that since it is from a full screen graph, dependencies may not be computed correctly. When I work in preview mode, however, it seems to work just as I expect. And looking at my student work, when I click through their screens, everything shows up as it should. The issue is that when I look at the summary or teacher view of the class, everything is marked incorrect.

I’m wondering if this is because the values in each graph are not active unless I am clicked into a particular student’s work? If so, is there any way to have the teacher dashboard properly display correctness based off of using the ans_0, ans_1, etc. special variables?

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Where does ans_1 get defined? I don’t understand how line 2 refers to ans_1 (which doesn’t even seem like a valid variable name to me).

(Also, I like your intro screen to show students how much they did instead of having to scroll through all the slides, since it desmos doesn’t take you to where you left off.)

This is a new thing I just learned from a reddit post. The ans variables are predefined and refer to the numeric value by line number in the calculator. Check this out: Graphing Calculator

That’s a fun find! As far as activity builder is concerned, I wouldn’t rely on that, though. There’s also a good chance that we’ll break that completely relatively soon.

Assigning each line to a variable and calling on those variables is still the best way to handle that.

Thanks. You know, I actually saw something that used this with binary numbers, and was wondering about that, but didn’t delve into.

Yeah, that’s the one I saw too. I wonder how many more secret things are hiding in the calculator.

Hi Jay - ok, that’s good to know. Easy come, easy go! But I’m still unclear about what happens when you try to use the correct sink in CL in a full screen graphing component. I changed the code in the above activity to just use a normal variable, and it still gives the same dependencies warning in the CL. Will the dashboard display correctly with student data if I use a normal variable instead of ans?

I think the warning is more because students can add or remove expression lines. If they remove, the line needed for correction and don’t replace it with the intended variable (or they add another line that duplicates another variable), then your correction will break. That’s the reason the warning icon is a more “gentle” color instead of the blaring yellow/orange.

Daniel has about summed it up. Basically, its possible to for students to “break” what you set up because they have the ability to change anything in the calculator. Even if you create correctness variables and hide them in a folder, there’s still a chance that the student will enter another instance of that variable and break that calculation.

That makes sense in terms of dependencies. But what I’m still confused about is why the correctness checks are not working in the dashboard view while they do work correctly in the individual student view, and whether this is due to an issue with the “ans” variables, or inherent in working with the fullscreen graphing calc.

Yeah, I wouldn’t rely on that hack in activity builder. Especially not in a full screen calculator (where a student could reorder the expression list) and ESPECIALLY not for anything related to dashboard correctness.