Context: a very basic level statistics package computer lab. A scatter plot is produced for one integer variable versus another integer variable. The students are asked why the points form a grid pattern. Students are 1st year undergrads.

Problem: I am struggling in my attempts to come up with a clear question, that allows the students to get to see (...by 'thinking'...) that the discrete plot positions are due to the variable's data type. Using terms like 'class of the variable' is currently unlikely to be in their vocabulary. Forming a question that does not obviously contain the answer evades my befuddled brain.

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    $\begingroup$ I'm voting to close this question as off-topic because it's about the contents of a specific discipline. I can migrate it to Mathematics Educators if you'd like? $\endgroup$
    – ff524
    Dec 5, 2016 at 15:38
  • $\begingroup$ My mistook! Apologies for the wrong forum. Please feel free to move it!! $\endgroup$
    – Big Old Dave
    Dec 5, 2016 at 15:52

1 Answer 1


Make an assignment that has the students find that scatter plot for continuous random variables. And as a second part of the assignment, make them do the plot you describe. Ask them to describe qualitative differences in those two plots and explain why this is.

Ideally, try to make the plots qualitatively similar except for the discontinuities.


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