Welcome again to the experiments' world! Do you know that with only a bottle, rubber gloves and a little bit of patience we can make a repiratory system? It' very easy! We just make a hole at the bottom. We take two straws and we stick two rubber fingers at the end. We put them inside the bottle. We add the diafragm at the bottom (another glove) and here we are. We can see how the rubber fingers are filled with air and then become empty again.