So in the meantime, if plants use air and water to grow, how can we represent this? How is it possible that we can add more air to something?
Using a soccer ball and a scale, students saw how we could put more air into it. We also used some syringes (with our fingers on the top) to see how we could compress and expand the air. From all our discussions, we realized that like water, air must be made of small pieces, too, with lots of empty space around them! We established consensus for what this looks like, and we'll be using this evidence as we wrap back around to plants getting the matter they need to grow soon: