When is a Line Not a Line?

3rd Grade Line Plot

3rd Grade Line Plot (From K12Math Passion Third Grade Written Assessment)

After a long hiatus, I am finally getting back to my assessment project.  The end of the third grade assessment is in sight!  As I work to understand each standard and turn it into an assessment question, I do a fair amount of checking to make sure (1) I’m using appropriate levels of problems and (2) my assumptions are good.  (I don’t always succeed, but that’s another story!)  This check is particularly important with elementary topics because my credential and most of my experience is with secondary math.

Two of my favorite sites for checking my assumptions are IXL Math and Illustrative Mathematics.  They are both very organized and easy to use.  IXL Math has lots of practice problems for each standard and Illustrative Mathematics has amazing tasks and a great interactive graphic showing the domains across grade levels.  (I’ll be using both of these sites over the summer with my 3rd and 4th grade tutoring students.)  There are others, of course, and I also use Google to research topics.  (If  you have a favorite site, please share it in the comments!)

Thank goodness I checked my assumptions about line plots (3.MD.B.4).  I don’t know about you, but when I think of line plots my brain constructs an image of coordinate pairs connected by line segments.  You know, something that has lines in it.  So, I was a bit surprised when I Googled “line plots for 3rd grade” and images of stacked X’s came up on my screen.  (See example above.)

Okaaaay.  Hmm.  Well, the making-a-line-plot standard doesn’t have an image of a line plot.  So, I did a little digging and discovered that, apparently, in the 3rd grade world a line plot looks like stacked X’s.

Don’t get me wrong.  I think the stacked-X’s-as-line-plot is an outstanding stepping stone between bar graphs or pictographs and traditional line plots.  I understand it’s an important bridge, which will greatly help students make the transition.  In fact, I hope teachers facilitate this transition by eventually asking students to draw a dot at the top of each stack of X’s and connect those dots with line segments.

It’s just the name that gets me: line plot.

I realize I’m a very literal person, and third grade was a LONG time ago, but I think even third grade me would be confused.  “Where are the lines?”

When is a line not a line?  When it’s a third grade line plot, of course.  Anyone can see that.