Importance of Meaning

I had this interesting experience teaching graphing to my 7th graders. I've been revamping my 7th grade algebra curriculum. For a couple of weeks now, we have been graphing some "real-life" of at least life-like data that have required my students to work with all kinds of numbers: from the very large to the very small, as well as decimals and fractions, and not just nice, even numbers like in our text book. They have displayed impressive flexibility as problem solvers as they try to figure out appropriate scales to graph these numbers. Just the other day I asked them to fill in a table and graph seven points that fit the rule y=3x+1. With their tables correctly filled out, they struggled to graph the integer coordinates. I saw several graphs set up with inconsistent scales--a problem I thought we had gotten over a while back. I have to say, I was pretty stumped. Perhaps it was the negative coordinates that gave them trouble. But I'm tempted to say that it was the abstract nature of the problem. Did the problem lack meaning, therefore making it more difficult to accomplish? This is an idea that I will be ruminating on...