So on the lesson plan it says if students finish the unplugged activity early. You could challenge them to figure out a way to test if the shapes are touching even if they are drawn on a different line. I am wondering if anyone has a potential answer to this? I like this idea and will try to figure it out on my own here soon probably, but if anyone had an answer to that would be nice.
Here are a couple resources to check out that discuss this topic.