Charge! – Activity Makeover Series

Background. I’ll share an activity. Offer some ideas on what’s wrong. Invite you to share your own diagnosis/treatment. Then (end of week) share an upgraded version of the activity. (More details about this series are available here.)

Activity and Diagnosis

A couple years ago, I sat against the wall in my sons’ bedroom, taking screenshots of my smartphone once every four minutes for an entire evening. (Why, you ask? For math!)

The result: Charge! (quite likely my only decent entry into the world of three act tasks).

About a year ago, I created an Activity Builder version of the task. And I’ve never been satisfied with it.

I think it’s better than nothing at all, but undeniably worse than the slide-driven, conversation-rich, paper-and-pencil version I posted on my blog a while back.

When it comes to the Desmos activity building code, this activity—even in its AB-powered form—succeeds on several fronts, including “create problematic activities” and “connect representations” (among others).

However, it struggles in ways that overshadow its strengths. Most notably:

#5 – Give students opportunities to be right and wrong in different, interesting ways. The AB version of Charge! feels too scripted. Too narrow. Rather uninteresting. “Do this. Now this. Next, this. Now do this.” And so on, all the way through the activity. There’s really just one path, and the activity leads students along it with minimal opportunity (or even need) for careful reflection or critical thought.

#8 – Create objects that promote mathematical conversations between teachers and students. This is a tricky one. I believe the activity could generate classroom discussion, but that the sheer number of screens works against that possibility, rather than in support of it. Let’s assume a 50-minute class period, with 45-minutes dedicated to this activity. That’s just 2.5 minutes per screen, which isn’t terribly conducive to classroom discussions. It might be wise to trim the number of screens so that there’s room for deeper discussions on a smaller set of screens.

#13 – Ask proxy questions. Would I recommend this activity? Nope. Not in its current form. I’d be much more comfortable recommending the original slide-based version. With the activity parsed into 18 step-by-step style screens, there’s no one screen with anything really interesting happening on it. One of my colleagues likes to consider the quality of an activity by asking whether any of the work students do on a given screen could be considered fridge-worthy. In other words, if they could print it out and take it home to show mom and dad, would it end up on the fridge as a proud display of something deep or delightful? Again, because I’ve chopped the interesting work in Charge! into 18 tiny bits, the answer is no. Nothing fridge-worthy in this approach.


  • Will you offer your own diagnosis? A second opinion of sorts? What do you think is wrong with this activity?
  • Better yet, will you offer suggestions for your own treatment? How would you make this activity better?
  • Better still, will you build and share a new, better activity that addresses the shortcomings identified in one of the diagnoses?

Drop a line (or two) in the comments, or let me know what you think on Twitter (@mjfenton).

I’ll be back Friday with a new treatment of my own.


Comments 4

  1. I am uncomfortable with the part of slide 5 in the Desmos version where you say “For example, 9:02 with a 5% charge would be (0, 5).” I think you can allow students to model that point in a way that makes sense to them. They may plot (2,5) and be able to interpret the points correctly. Alternately, if they try plotting (902,5), there is an opportunity for conversation there!

    Can we give students more chucks of the data and give them an opportunity to revise their model? If this were my real phone in real life and I needed to know when it would be charged, I would be checking on it every so often to see if my estimate was still on track. We could give them the data from 9:02 to 9:30. Are you still happy with your model? Your prediction? Okay, from 9:30-9:50. Still happy? okay, 9:50-10:30. How about now?

    What if different groups of students had different data points along the way & they discussed the models they came up with?

  2. Disclaimer: I’ve only ever done this without Desmos and I’ve only done it with 6th graders who have some exposure to ratio tables and graphing, but not linear equations.

    I’m trying to figure out what Desmos adds to the activity. I couldn’t use it because my students would be lost when it came to creating a trend line. To solve this, they really have to think about rates and extending those values as a table. In the end, their solutions probably closely match a student’s solution who used a graph.

    With that being said, this activity pigeonholes students into one way of doing it, and even for students in higher grades, I’d like to give that option to explore it differently. I think Desmos might be a good tool for students that want to explore graphing, but how do you manage that? As an activity, you’d have to say something like…”if you’re using a graphical approach, go to slide 7. If you’re doing some other weird thing, just keep doing what you’re doing”.

    In the end, maybe this doesn’t work in activity builder. Maybe you could just suggest using the Desmos calculator if you notice them working in that direction.

  3. I’ve looked at this activity in the past but have never used it for the reasons stated above: It seems a little advanced for my kids in the way it requires them to solve the problem. I’ve often struggled with the idea of using Activity Builder for 3 acts…I think it’s hard to create an activity without guiding students to solve a problem a certain way and one of the beautiful things about 3 acts is allowing students to determine what information is important (to an extent) and what to do with it.

    Another thought…I know different phones show different things when charging, but my phone shows “Approx. 1h 7min until fully charged”. It might be interesting to frame the question in the form of “How accurate is that?” Unless that means having to completely recreate the screenshots (which I don’t suggest you do).

  4. I would agree that the paper / pencil / discussion version of this 3-ACT is superior to the current Activity Builder version. As Elizabeth and Nathan have referenced, 3-ACTs are maybe best if served without AB.

    That said, I do think utilizing the Classroom Conversation Toolkit w/ teacher pacing and pausing might be a benefit to this activity. I think the first four slides are a great ACT 1. The Activity Builder gives students an anonymous voice to make sense of the problem and generate what information would be helpful to solve the problem. I would recommend using slides 1-4 as ACT even if I were to complete ACTs 2 and 3 w/ pencil and paper.

Leave a Reply