These are a couple pages I do on defining linear relationships. This is an example of an ISN page that I do after the kids have already developed the idea themselves. We spend a couple days looking at and graphing different patterns and they have a good idea of which ones will come out to be straight lines.
Next I give them a little slip of paper with the four charts on them. They cut them out and decide which are examples and which are non-examples. Once they have been checked, they tape them down. At this point, it gives me a really good idea of which kids get it and which are still a little unsure.
On the left side (we did this on a different day as part of a station activity) I have the kids create their own patterns; one that is linear and one that is not.
This activity gives me an even better idea of which kids get it, and how well they get it. For the kids that are still a little unsure, they will usually just modify some of the examples from the Frayer chart on the right page. I can tell which kids understand it really well because they will usually come up with more creative patterns.
Linear functions is a really big idea in pre-algebra and algebra so this is an activity that I plan to use with my algebra kids next year. I love using Frayer charts for definitions because they give a much more complete picture of an idea instead of just a definition.