Graphing Mistakes – Analyzing Errors

My 8th graders are usually quite terrible at graphing at the beginning of the year. It amazes me. This year I gave my honors students a pre-assessment which included a problem asking them to create a graph from a table of values.  Many of them used a weird scale or just didn’t label the scale at all.  A good chunk of them left off the labels for the independent and dependent variables. A surprising number of them created bar graphs.

I was planning to have my honors students take a quiz on Tuesday of last week. But on Monday night I lay awake thinking of how much I was dreading looking at their terrible graphs, when it hit me. Why am I giving them a quiz if I already know that they are going to perform terribly? I got to work early on Tuesday morning and quickly wrote out this assignment called “Graphing Mistakes”. I created six incorrect graphs – each highlighting one or two of the errors that I commonly see on the first graphing assessment of the year.

Each group of 3-4 students received one paper that looked like what you see above.  On the back of this paper was a large, blank graph for them to complete as a group.  Each student received a paper to fill out with descriptions of the errors on each graph.


I actually didn’t care too much about what they wrote on the paper, but I figured it would be good for them to have some individual accountability.  I was much more concerned about the discussions.  And boy did they discuss! It was awesome. At TMC14 this summer, @cheesemonkeysf talked to us a lot about the power of having students and groups take ownership of classroom behavior and learning. That’s exactly what happened with this activity. I could talk to students about the importance of correct labels and an even scale until I’m blue in the face and they still wouldn’t get it.  But hearing it from a classmate suddenly made it real.

So in case you think that I’m starting to wax Pollyanna-ish about this activity and its awesome power to debunk all misconceptions about graphing, let me tell you what didn’t go well.  Some groups weren’t able to identify the errors or they only found one or two of them. Some groups identified features of the graphs as errors that actually weren’t errors at all.  I made sure to debrief this activity afterward with the whole class to be sure that everyone recognized every error.  When groups were creating their ‘correct’ version of this graph, several of them recreated the same errors that they had just discussed.


Old habits die hard, I guess.

My honors students took their quiz the next day and their graphing was much better than what I have seen on this quiz in previous years.  However, there was one error that kept popping up over and over again.  It looked like this:




Check out the scale on the y-axis. Not so even, is it? I had forgotten that so many of my students made this mistake.  When I orginally made my ‘Graphing Mistakes’ group assignment, this error wasn’t on there. One of my coworkers remembered it and added it to the assignment later that day (you see it on Graph #5), but not until my students had already completed the activity.

I’m posting two links to this assignment.  The first is a PDF of pretty much exactly what you see here. (I liked the idea of creating it as a PDF because I wanted the graphs to be hand-written so that they’d look more like student work.)  The second is the Word Doc template that I created for this activity, in case you’d like to edit it or create something different or highlight different errors more common among your students. If you do create something, please share it. I’d love to see what you come up with.

Graphing Mistakes PDF

Graphing Mistakes Template Word Doc


2 thoughts on “Graphing Mistakes – Analyzing Errors

  1. Pingback: Mathematical Desk Murders (AKA Failing to Use an Evenly Spaced Scale!!) | Ms Moore Math

  2. Pam

    This was excellent activity for my students. I changed it up a little and told them to choose the correct one. Only two students figured out that all were incorrect, but the others really tried to make graph 1 and graph 5 work.


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