106 days of creation, Exp 18

We have really been enjoying these experiments! We are working on Experiment 18. After we seal the neck of the glass bottle with play-doh, the directions say to blow into the straw until the water rises halfway up the straw. When we do that, the water level doesn’t move. This makes sense to me because we can’t add a substance to the bottle that is already filled with water and air then sealed. We tried sucking water up the straw but that didn’t work either, for the same reason; we can’t take a substance out of the sealed space without replacing it with an equal amount of some other substance. I even tried unsealing the bottle and blowing the air in but, of course, that didn’t cause the water level to rise, it just made bubbles in the water that immediately pop when they reach the surface. Does anyone know what we’re doing wrong? Thanks!