I'm trying something new with my Friday estimation jar activity. Typically we practice making reasonable estimations, group the candy by tens, count it, and eat it. I'm attempting to integrate the open number line and just better number sense. It's kind of an experiment. Here's how it's going so far.
The person who brought the estimation jar filled with wrapped candy chooses three people to share their estimations which I write on the smartboard. I draw an open number line and we put the estimations in order on the number line with proper spacing. Then I draw another number line on the board and we start counting the candy. When we get to ten, I talk about how I could make ten small hops or I could simply make one hop to ten. Every time we count another ten, I make another hop and so on until we've counted all the pieces. Finally, we return to the three estimations from the beginning of the lesson, find where those numbers fit on our new number line, circle them, and see how close they were to the actual number.
Here are several examples.
I'm tweaking as I go, but I think I'm on to something that will help my mathematicians grasp the open number line better. Eventually, I envision the kids doing this with me at their desks with their own number lines, following what Regie Routman says. I do, we do, we do, we do, you do.