Student names were on regular-sized sticky notes. To adapt it for the secondary level, I would create a similar chart for each class, but smaller - perhaps on a piece of construction paper - and use the smaller sticky notes. That way I could still have each class posted on a wall. Another option is to create just one chart with numbers only and have each student assigned a number.
We might not get to every student in one lesson, but with creative structures like this one, we can be sure to come back to them in the next! When you set up your classroom for next school year, how will you include structures for increasing participation?
For more ideas, keep following and look for an announcement in the fall about my newest book!