Most students had no difficulty identifying the equations as linear or non-linear. Where there was some discussion between students was when they were sorting the tables. Within each pair, it seemed like one student knew that the slope had to be constant (or the same) when looking at how y changed in relation to how x changed.
Where many students need a little more work is on using mathematically precise language. The response below shows an example of an answer to the two summary questions. The questions were: 1) How can you determine if an equation is linear or non-linear? and 2) How can you determine if a table of values represents a linear or non-linear relationship?
I think we will begin class tomorrow by critiquing this response to the two summary questions. I'll blog about how that went along with a different sorting activity tomorrow.