Parallel Lines – 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

Some months back, I wrote an activity called Parallel Lines. Here’s the description:

“In this activity, students explore connections between the graphs and equations of parallel lines.”


It’s not awful. But it’s far from great. It really struggles with two principles of our building code in particular:

#4 – Create problematic activities. It’s not clear to students what they’re doing—or why they’re doing it—until the end of the activity (or maybe even at all).

#5 – Give students opportunities to be right and wrong in different, interesting ways. There’s really just one correct path through this thing. And I don’t believe there are interesting ways to be wrong here, either. Bottom line: expect a lot of similar, uninteresting student responses. I’m not sure that’s the best fodder for rich classroom discussion.


  • 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. Asking students to state what they already know about parallel lines might be a better start. Also including something concrete (a story, a model) for students to follow would be great. The abstract “play around with the sliders” when students don’t know or don’t have anything concrete to represent those sliders is confusing. I would suggest to ask for a guess or prediction on “what” makes lines parallel before manipulation. That way, students can see if they were correct in their thinking.

  2. Firstly, your approach and honesty to refining your activities is wonderful to see. Secondly, here are my thoughts on this; Why the form y = mx + c? Does this form actually hinder the development of ratio between coefficient of x and y being constant for parallel, if the form ax + by = c is used then there may be more scope for “which ones are parallel” type questions and “create your own equation” with multiple equations satisfying given conditions.

    I look forward to seeing what you do with this activity.

  3. Thanks for the opportunity. My shot at a treatment using the context of parallelograms.

    It needs more work. There is probably a need for more practice before the challenge to help identify misconceptions. The teacher is going to need to bring out the ideas about parallels and equations using teacher pacing in the middle screens. In particular the what do you notice and the multiple choice screen need class discussion. The wording on the challenge screen and seeking multiple solutions also needs work. I am not certain it matches the ideas you were hoping for in the original.

  4. Pingback: Parallel Lines v2 – Activity Makeover Series | Reason and Wonder

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