Tag: Desmos

An Assessment on Desmos

An Assessment on Desmos

I gave my two Algebra classes an assessment on Desmos covering linear functions. The idea started as a joke – I told a student who had found Marbleslides challenging that I’d put some on the test. As I thought about it more, though, I decided that assessing with Desmos would be a great idea.

I used Activity Builder to create the assessment. The easy-to-use, intuitive interface made creating the assessment fairly easy, but I encountered a major unexpected challenge. Designing worthwhile questions proved much more difficult. It no longer made sense to ask students to simply graph or write the equation of a line. Instead, I focused on questions that ask students to describe how to graph a line, to explain why an equation’s graph would look a certain way, and to interpret a line’s equation in the context of a problem. This is actually the type of question I always want to emphasize but rarely do.

Desmos Assessment 3

Consider the question above. If I had asked students to simply graph the line given by the equation x=5, they might have been able to do so without truly understanding the equation for a vertical line, and I never would have known.

Desmos Assessment 10

Similarly, this word problem went beyond simply asking students to write an equation to making them connect the mathematics to the situation being modeled. Each of these five students wrote a correct equation, but their understandings of the problem clearly differ. So too does their ability to express their reasoning, something seen in the following example also.

Desmos Assessment 9

Do these students understand the relationship between the graph of a line and its equation? To an extent, they certainly do, but their explanations also reveal some gaps in their understanding. What I find most interesting is how students managed to express their thinking in so many ways. Some used mathematical vocabulary; others didn’t. Some provided precise explanations that anyone could follow; others used ambiguous language that might obscure their meaning. For as much as I think I emphasize communication in my classroom, my students’ responses make me want to spend even more time refining our ability to share our thinking in a clear, concise manner. Perhaps including more problems that call for explanations on each assessment will help me move in that direction.

And that’s probably my favorite part of using Desmos for an assessment. It’s so much easier for students to explain themselves on the computer than it is with pencil and paper. Consider the following responses.

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I know my students, and I can say with complete certainty that they would have written much less on a paper-and-pencil test. And I would have missed out on seeing and understanding their thinking. Between this problem and the one shown in the image at the top, I developed a clear picture of what my students know and don’t know about y-intercepts, something that may not have been possible the way I typically assess.

And, of course, Marbleslides. The incomparable joy of Marbleslides.

Desmos Assessment 4Desmos Assessment 11

I don’t see a lot of students absolutely beaming during tests, but I did this time. That student I mentioned earlier – the one who found Marbleslides so challenging – successfully collected all of the stars on this assessment, and she was so incredibly happy. Seeing her smile made the entire assessment worthwhile.

I suppose it’s worth discussing the nuts and bolts. Grading wasn’t really easier or harder than a pencil-and-paper assessment. It was just different. Take a look at the dashboard below.

Desmos Assessment 1

It’s easy enough to grade a question when a student gets a check, but everything else required me to take a closer look. Sometimes, as with the following question, that was pretty easy to do.

Desmos Assessment 8

I can quickly glance through student responses and get a sense of common misconceptions. But with questions that require an explanation (or an input that doesn’t get verified), I have to take the time to look through everyone’s individual work. And that’s totally fine. That’s what grading is usually like, and I think it’s important to see and assess each student individually. Desmos actually made it easier to do this.

As far as actually tallying scores and providing feedback, I had to improvise. I used Google Sheets to create a little rubric. I included a place for a numerical score and a place for brief comments on the individual problems. I also let my brain rest and made Sheets calculate the grades for me. Here are some examples.

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I printed these little rubrics and returned them to students. Then, I un-paused the activity and allowed students to look back at their work and correct it if they so desired.

Other miscellaneous thoughts:

  • The Ohio AIR test uses the Desmos graphing calculator, so this sort of assessment should help my students prepare. It’s also easy to create AIR-type questions using Desmos.
  • There isn’t really a way for students to “turn in” the assessment. I just told them to close the tab and shut down their Chromebook when they finished. This is totally fine; it’s just something I had to tell them about a hundred times.
  • It’s relatively challenging to monitor students to make sure they’re not just using Google to search “how to write a linear equation” or using Discord to ask each other questions. I emphasized honesty and integrity at the beginning, and that seemed to do the trick.

If you’re wondering if I’d give another assessment using Desmos, the answer is a resounding yes. I’m actually designing two more assessments (one for Algebra, one for Math 8) right now. And my colleagues have agreed to try using Desmos for one of their assessments!

Thank you to Desmos for being awesome! Thank you to Julie Reulbach and Jonathan Claydon for introducing me to the idea of Desmos assessments! Thank you to my students for making my job wonderful!

Update: Wow! This post received quite a response on Twitter! Here’s the link for anyone interested: https://teacher.desmos.com/activitybuilder/custom/5bc52d70744e4b427f3ce5a6

What Do My Students Really Know? Part 1

What Do My Students Really Know? Part 1

My two Accelerated Math 1 classes have been working with sequences. They have completed some investigation problems to develop vocabulary and to grapple with the characteristics of different types of sequences. We have built definitions of explicit and recursive formulas as well as of arithmetic and geometric sequences, and as a class, we came up with explicit formulas for both of these types of sequences. Their work has impressed me, especially given that we’ve done all of this using function notation, which is totally new to everyone. Students don’t even seem particularly troubled by some of the more challenging problems (such as figuring out missing terms when given two specific terms or determining the term number for a far-off term) that have frustrated some of my past classes. I know that they need more practice, but overall, I’m pleased with their progress.

For practice, we completed a matching activity in which students had a card with either the formula for a sequence or the sequence itself. They had to find the student with the matching card. I designed the sequences to be fairly similar so that students really had to think about which sequence went with which formula. It wasn’t enough, for example, to notice that the first term of the sequence matched up with the formula because multiple sequences had the same first term.  My students handled this activity pretty easily.

I wanted to try something similar with Desmos, so I made this Polygraph activity. It features eight numerical sequences and eight explicit formulas. I expected students to ask questions like: “Is your sequence arithmetic?”; “Is the common difference positive?”; and “Is the first term negative?” Although I certainly saw questions like those, I noticed that many students used imprecise language and pursued a line of questioning that lacked a logical progression meant to eliminate possibilities. Their work surprised me and has made me wonder what they have really learned. Here is some of their work along with my commentary.

1

The questions about negative numbers make sense on the surface, but all decreasing arithmetic sequences will have negative numbers eventually. Is it important that this student was referring to the first three terms without saying so? Had I been the picker, I may well have answered “yes” to that question even if my sequence only displayed one negative number. Substantial mathematical background allows me to focus on this sort of nuance. How do I help students refine their language to remove the ambiguity that I see? Or am I seeing an issue where one really does not exist?

2

Does the formula for a sequence count as a sequence? Should that first question be worded as “a numerical sequence” to avoid confusion? Would n-1 count as having a negative? Does using “over” instead of “greater than” present a problem?

3

Although I’m happy to see “arithmetic” used correctly, the word “decimals” worries me. I’m not sure that “decimals” has a firm definition in my students’ minds. These students seem to be referring to numbers containing a decimal point, which makes sense, but I wonder what they think of 3.2\times 10^{3}. Does that count as a decimal? Perhaps a better question would ask about non-integers.

4

Sure, these questions get the job done with minimal ambiguity, but I’m not a huge fan of the final two questions. Without a need for vocabulary like “common ratio,” I suppose it makes sense to ask these questions. Maybe I need to force students into choosing between two geometric sequences with the same first term. But would students then simply ask about “the number in parentheses” or something similar?

5

Ah! Here’s a misconception! Seeing multiplication in the equation led the picker to call it a geometric sequence. This is why I love Desmos activities – concrete evidence of students’ understandings and misunderstandings that I can immediately work to address.

6

Another opportunity for improvement on my part! The two sequences remaining after the first three questions differed in two regards – their first terms and their common differences. A possible revision might be to change the highlighted formula to f\left ( n \right )=12+6\left ( n-1 \right ). This would even make a question about subtraction useless, so it should elicit a question about the common difference.

Lots going on here. Plenty of great vocabulary here (e.g. “explicit formula” and “common difference”) as well as some great questions about odd and even numbers. I’m particularly fond of the question “do you add to get to the next term.” Sure, I’d love to see “arithmetic sequence” show up in that student’s vocabulary, but it’s hard to fault a student for a description that just works.

12

Just a fascinating line of questioning here. Only one of the three visible sequences has exactly two negative numbers, but the students here only considered the visible terms. Why did the guesser asked about negative numbers anyway? Wouldn’t asking if the sequence increases (or decreases) be simpler? And to follow one interesting choice with an even more interesting question…wow! Why does this student bother including the word “arithmetic” in this question? Both of the sequences are arithmetic. And why ask if it’s adding 7 instead of simply asking if it’s increasing? This sort of specificity doesn’t really add anything other than the risk that one of the students miscalculates and leads the other astray. I wish I could have been inside this student’s head!

So much to say about these… One student was extremely curious about the starting number. What does that say about that student’s understanding of sequences? Several students asked about function notation rather than asking about formulas or equations. How about the student who asked about positive numbers, even numbers, double-digit numbers, AND the number 4? Yes, these questions got the job done, but what do they really tell me about my students’ understanding of sequences?

As you can see, my students used all sorts of vocabulary. They used lots of different math terms, but they didn’t use as much of the sequence vocabulary as I expected. On the one hand, I’m proud of their ability to use what they know and what they’re comfortable with to find success. But I wonder what this all says about our work with sequences. This Polygraph activity certainly differs significantly from the work we’ve been doing. Students need to do more than just perform calculations and interpret numbers. Polygraph forces students to wrestle with sequences in a unique manner and to draw distinctions between sequences represented numerically or as equations. Perhaps in the face of such a challenge my students retreated to the most natural language. Perhaps their understanding of sequences isn’t what I thought it was. Perhaps the numerical sequences and explicit formulas I chose did not lend themselves to the sort of questioning and language that I had hoped for.

So what does this all mean for my teaching and for my students’ learning? I actually feel like I’ve done a better job with sequences than I ever have before. So much more of our work this year has involved thinking through and solving problems. But maybe I haven’t gone far enough in including rich, meaningful tasks. Or maybe this was just a necessary step on the path toward mastery. As we continue working with sequences and eventually use our sequence knowledge to develop linear and exponential functions, I look forward to further probing my students’ understandings and challenging them to engage more deeply with the mathematics.